らしい

らしい at the end of a sentence means "apparently" or "I hear": you are passing on something you learned from others or worked out from indirect evidence. It follows the plain form of a verb or an い-adjective, and a noun or a な-adjective directly, with no だ.

The tense goes on the word before らしい, not on らしい itself.

In the present, a noun or a な-adjective takes no だ.

• × 静かだらしい → 静からしい
• × 学生だらしい → 学生らしい

らしい, そうだ or みたい

Hearsay そうだ passes on what you were told, plainly, often with the source named. らしい is vaguer: the source is rumour, or you are drawing a conclusion from it. みたい rests on what you have seen or experienced yourself.

"Typical of": noun + らしい

After a noun, らしい can also mean "having the qualities a real X should have", "true to X". In this sense it is an ordinary い-adjective and can come before a noun.

So がくせい学生らしい can mean "apparently a student" or "just as a student should be". The rest of the sentence decides: before a noun or with らしくない, it is almost always the second.