なさい (romaji -nasai)
- (informal) combines with the verb stem to create an imperative as a kind of strong request
- Yoku kikinasai！
- Listen up! (as to a child or spouse)
- Koko ni namae o kakinasai.
- Write your name here.
- Ano neko o minasai.
- Watch that cat.
This is a suffix, attaching to the 連用形 (ren'yōkei, “stem or continuative form”) of verbs.
This is stronger than a simple request, and is considered somewhat informal. This may be used as a way of issuing a command, such as a teacher prompting a student to pay attention, or a parent scolding a child.