also: いかなくちゃ
expression
I've got to go; I must be going
A set expression meaning 'I must go' or 'I have to leave'. It is a contraction of 行かなくてはならない, with the ending omitted. Used when the speaker feels obliged to depart.
See also: 無くては (なくては)
もう遅いから、そろそろ行かなくては。
It's late, so I should be going soon.
すみません、用事があるので行かなくちゃ。
Sorry, I have something to do, so I've got to go.
Even more casual contraction of 行かなくては, common in very informal speech.
Contraction of 行かなくてはならない (must go), with the final part omitted. The なくては pattern expresses obligation.