Grammar Point
expressions (phrases, clauses, etc.)
exp 
word usually written using kana alone
uk 
かもしれない

may, might, perhaps, may be, possibly

Verb or い-Adjective + かもしれない

Used to express a possibility that something might be true or might happen. It indicates a lower level of certainty than 'probably' (でしょう/だろう).

Verb

The dictionary form or past tense form of a verb is used to indicate a possibility of an action.

It might rain tomorrow.

I might have lost my wallet.

い-Adjective

The dictionary form or past tense form of an い-adjective is used to indicate a possibility of a state.

The movie might be interesting.

The food might have been expensive.

Note

In casual conversation, かもしれない is often shortened to かもしれん or just かも. When used with verbs or い-adjectives, the dictionary form or past tense form is used directly before かもしれない.

Noun or な-Adjective + かもしれない

Used with nouns and な-adjectives to express possibility. Unlike verbs and い-adjectives, the copula だ is omitted in the present tense.

Noun

Nouns are followed directly by かもしれない in the present tense, or by だった in the past tense.

That person might be a teacher.

He might have been a student.

な-Adjective

な-adjective stems are followed directly by かもしれない in the present tense, or by だった in the past tense.

The room might be quiet.

The test might have been easy.

Note

Do not use だ after a Noun or な-Adjective when followed by かもしれない in the present tense. For example, '学生だかもしれない' is incorrect.

Words: 
かも知れないかもしれない
Radicals of radicals