conjunction · to suppose something to be true or to take as a premise

假定他还没走，我们现在去还能见到他。

verb · assumed to be such; existing only in theory or as a premise

这只是一个假定的情况，并不是事实。

noun, verb · an assumption or proposition taken as a basis for reasoning or investigation

警察假定嫌疑人还留在城里，并封锁了所有的出口。