接尾辞. Endings which can be added to the end of a word and change its meaning or function in some way. Often divided into inflectional (屈折的) and derivational (派生的), although it's not always clear which category a suffix belongs to. Suffixes and prefixes are both types of "affix". Often referred to as 接尾語.
Examples of suffixes in Japanese are
- ～さ as in 早い → 早さ (cf. En. -ness)
- ～的 as in 一般 → 一般的 (cf. En. -ly)
- 接尾辞 on Japanese Wikipedia