1A group of similar things or people positioned or occurring closely together.

一丛丛米色鲜花。

1. 1.1Astronomy A group of stars or galaxies forming a relatively close association.
   〔天文〕星团；星系团
   there are several clusters in Cassiopeia

   Example sentencesExamples

   • Galaxies often congregate to form clusters of galaxies.
   • A double star cluster in a satellite galaxy of the Milky Way is pictured above.
   • They're searching for superdistant, ancient protogalaxies lurking behind huge clusters of galaxies closer to Earth.
   • We know what matter looks like today because we see galaxies, galaxy clusters, and galaxy superclusters.
   • Astronomers may see meteors produced by the annual Perseid shower, before pointing their telescopes at distant galaxies and star clusters.
   • We sometimes use the word nebula to refer to galaxies, various types of star clusters, and various kinds of interstellar dust or gas clouds.
   • There exists a well-defined population of material aggregates in the Universe - planets, stars, galaxies, and clusters.
   • Among the many mysteries in the universe is the dark matter in galaxies and clusters.
   • There is a higher proportion of elliptical and fast-rotating spiral galaxies in dense clusters than in small groups.
   • Astronomical observations have confirmed more or less beyond doubt that stars, galaxies and clusters of super galaxies are receding from the earth and from one another.
   • These large dark clouds may eventually evaporate or, if there are sufficiently dense condensations within them, give birth to small star clusters.
   • Astronomers have long exploited this correlation between age and color to study the ages of stellar populations in star clusters and galaxies.
   • Studies of two distant galaxy clusters have found that galaxies formed relatively early in the history of the Universe.
   • Two vast cavities extend away from the super massive black hole in the cluster's central galaxy.
   • An excellent example is the cosmological problem, since it contains scales of interest ranging from that of a single star to that of a large cluster of galaxies.
   • By the end of that process, matter could move and coalesce on its own, forming planets and stars, as well as galaxies, clusters, and superclusters.
   • The most easily visible part of galaxy clusters, i.e. the stars in all the galaxies, make up only a small fraction of the total of what makes up the cluster.
   • A team of European astronomers, including several from the UK, have uncovered a super star cluster in our own Galaxy, the Milky Way.
   • The centre of our galaxy lies within a cluster of stars in the constellation Sagittarius.
   • Caroline also compiled catalogs of star clusters and nebulae.
2. 1.2Linguistics A group of consonants pronounced in immediate succession, as str in strong.
   〔语言学〕辅音群，辅音连缀（一组连续发音的辅音，如strong中的str）
   Example sentencesExamples

   • Consonants regularly occur in strings or clusters without intervening vowels: initially, as in stain and strip, finally, as in fetch and twelfth, medially, as in dodging.
   • The present orthographic system was introduced in the fourteenth century by the religious reformer Jan Hus, who instituted a system of diacritical markings to eliminate consonant clusters.
   • Let's say you're in a language that uses schwa to break up consonant clusters, but nowhere else.
   • Thus, our strong emphasis on onset clusters succeeded in inducing a small but reliable transfer effect.
   • This paper examines one aspect of second language syllable structure, syllable-final clusters, in the English of a Vietnamese L1 speaker.
   • I believe that the programme allows up to 9 consonants in a cluster, but only word-internally.
   • … if one chooses the Latin, French, or Italian language, since German is much more difficult because of its many closed syllables and consonant clusters.
   • The software was unaware of complex character clusters associated with consonant/vowel modifiers in Indian languages.
3. 1.3 A natural subgroup of a population, used for statistical sampling or analysis.
   抽样人群
   ten clusters from all the primary health centres were selected

   Example sentencesExamples

   • Using cluster analysis, a statistical method that determines subpopulations in a group, three distinct patterns of behavior emerged.
   • Moreover, except for this one attempt nobody has tried to use cluster sampling to measure deaths by violence.
   • The researcher used cluster sampling in this study and also eliminated participant duplication.
   • A common approach is to initially treat every sample as a cluster and to join the closest clusters together.
   • To determine how many natural clusters exist within a given sample, various stopping rules have been developed.
   • Cluster analysis was used to determine the clustering of populations in multivariate space.
   • However, an expert at the Institute of Occupational Medicine in Edinburgh said it was ‘probably true’ that most clusters of illness happened by chance.
   • A major issue in any study is maintaining the distinction between statistical clusters and their geographical expression.
   • The critical thing to understand here is that statistics cannot tell you the likely deviation of a cluster sample unless the distribution is random!
   • However, use of cluster randomisation rapidly leads to a doubling of the sample size.
   • The examples focus on the process of conducting a cluster analysis of transfer pricing.
   • This difference was significant, even in the rigorous statistical analysis for the cluster level design, controlling for confounding variables.
   • It says a long-term epidemiological study should be set up in the area to establish if there are any clusters of diseases which might be attributable to the radar's presence.
   • We also recruited a large number of clusters and performed statistical analyses taking cluster randomisation into account.
   • Policy makers should consider testing health service innovation using cluster randomised controlled trials with the hospital as the sampling unit.
   • As noted above, cluster sampling tends to underestimate the impact of focused violence.
   • Cluster sampling is a sampling technique where the entire population is divided into groups, or clusters, and a random sample of these clusters is selected.
   • Despite the small sample sizes for some of our cluster groups, many cluster differences still attained statistical significance.
   • These were considered sufficiently small to assume statistical independence within a cluster.
   • Each cluster should be a statistical scale-model of the entire population.
4. 1.4Chemistry A group of atoms of the same element, typically a metal, bonded closely together in a molecule.
   〔化〕基
   noble-metal clusters supported on an acidic carrier

   as modifier a cluster compound

   Example sentencesExamples

   • In the centers of these molecular clusters, called micelles, the molecular chains are packed together densely.
   • These cluster ions can, however, be broken up by a flow of dry nitrogen gas (curtain gas).
   • In metallic clusters, the metal atoms are either directly bonded through metal-metal interactions or are bridged by appropriate ligands.
   • Similar patterns are seen in small atomic systems, such as the closed shells of valence electrons in metal clusters.
   • A chelate is a chemical compound in which one atom is enclosed within a larger cluster of atoms that surround it like an envelope.
   • Absorbing a photon can force a photosensitive cluster of atoms to reposition a chemical bond and create a kink in a polymer chain.
   • Research has since shown that laser vaporization of graphite produces clusters of carbon atoms whose sizes range from two to thousands of atoms.
   • These clusters were once separate molecules, called amino acids.
   • Proteins containing iron-sulfur clusters play important roles in biological systems.
   • Nevertheless, there were no significantly supported clusters including molecules from both vertebrates and invertebrates.

1Form a cluster or clusters.

孩子们围聚在她裙边。

1. 1.1Statistics (of data points) have similar numerical values.
   〔统计〕（数据点）具近似数值
   students tended to have marks clustering around 70 per cent

   学生们的分数都在70分左右。

   Example sentencesExamples

   • Average clustering coefficients and standard deviations of the averages for node degree bins are shown.
   • Standard deviation is the measurement of how scores are clustered or dispersed in relation to the mean.
   • However, peer group bias appears clustered with instrument manufacturer.
   • Our analysis also ignored the fact that scores are clustered at practice level.
   • This method thus allows for clustering without a priori knowledge of the number of clusters present in the data set.
   • However, while a few genes do show rather high transition bias, most of the estimates cluster tightly around the median value.
   • In both analyses, we computed robust standard errors adjusted for clustering at the firm level.
   • Although there were outliers, the majority of the data points clustered around the population mean.
   • We have said that when multiple repeated tests are performed results will cluster around the ‘true’ value.
   • Similarly, in scientific data mining, algorithms seek to cluster, generalize, and classify patterns and correlations in databases.
   • We fitted town as a fixed effect and school as a random effect to allow for clustering at school level.
   • Standard errors have been adjusted for clustering within families.