forming the plural ［构成复数］
1
- of nouns adopted from Latin ending in -us构成来自拉丁语、结尾为-us的名词的复数：
foci
timpani.
2
- of nouns adopted from Italian ending in -e or -o构成来自意大利语、结尾为-e 或-o的名词的复数：
dilettanti.
USAGE
Many nouns derived from a foreign language retain their foreign plural, at least when they first enter English and particularly if they belong to a specialist field. Over time, though, it is quite normal for a word in general use to acquire a regular English plural. This may coexist with the foreign plural （e.g. cactus, plural cacti or cactuses） or it may actually oust a foreign plural. Note that not all Latin words ending in -us have a plural that ends in -i： for example, the Latin word apparatus is unchanged in the plural.