Masen

Masen is the negative form of the polite present/future tense in Japanese grammar. It is attached to the stem of a verb in the polite form, turning the ending -masu into -masen. For example, tabemasu (to eat) becomes tabemasen (do not eat / will not eat).

Most verbs form the negative by adding -masen to the verb stem. Examples include ikimasu (to go) becoming ikimasen, nomimasu (to drink) becoming nomimasen, and hanashimasu (to speak) becoming hanashimasen. The two common irregulars are suru and kuru: shimasu becomes shimasen and kimasu (to come) becomes kimasen.

Usage notes: Masen is used in polite or formal contexts and is the standard negative in the -masu form. It is not typically used in casual speech, where nai forms are common (tabenai, nomenai, etc.). To form a polite negative question, -masen ka is used, as in tabemasen ka? meaning “Would you not eat?” or “Aren’t you going to eat?”

Past polite negative exists as tabemasen deshita (did not eat / did not will eat) and similarly with other verbs. These forms preserve the same polite level as -masen in the past.

In summary, masen is the essential tool for negation in polite Japanese verbs, applicable to most verb types with a few irregulars, and it contrasts with casual negatives formed with nai.