The same kind or category of things; can also refer (in context) to persons of the same sort, including accomplices or associates.
この鳥は同類の中でも体が小さい方だ。
This bird is one of the smaller ones among its kind.
彼の行動は以前逮捕された者たちの同類に見えると言われた。
People said his actions looked similar to those of previously arrested offenders.
そんなやり方は同類の製品でも珍しい。
That method is unusual even among similar products.