- An angle greater than 90° and less than 180°.钝角：一个大于90°而小于180°的角
- radiocarbon
- radiocarbon dating
- radiochemistry
- radio collar
- radio compass
- radioecology
- radioed
- radioelement
- radio frequency
- radio galaxy
- radiogenic
- radiogram
- radiograph
- radiographies
- radiography
- radioimmunoassay
- radioimmunology
- radioing
- radioiodine
- radioisotope
- radiolabel
- radiolarian
- radiolarians
- radiolocation
- radiologies