限り【かぎり】

限り after a verb or an adjective sets a condition that has to keep holding: "as long as". It follows the dictionary form or the ている form of a verb, an い-adjective directly, a な-adjective with な or である, and a noun with である.

A noun takes である, not だ: ×学生だ限り. As a condition, 限り sounds firm and a little formal; in conversation "as long as" is just as often なら, or さえ with a ば-form.

ない限り – "unless"

After the ない-form, 限り means "unless": nothing changes until that condition is met. The main clause is often negative.

"As far as" – 知る, 見る, 調べる

With a verb of knowing or seeing, 限り narrows the statement down to what the speaker knows. The verb is in the ている or た-form, and では often follows. In a formal sentence the person takes の instead of が: わたくし私のしる知るかぎり限り.

Usage notes

These go beyond "as long as".

To the limit

できるかぎりできる限り is "as much as possible". After a noun with の, 限り is the limit of that thing: ちから力のかぎり限り "with all one's strength", こえ声のかぎり限り "at the top of one's voice".

Only this once

Straight after a word for a time, 限り means "only" or "ending with": きょう今日かぎり限り "today only", こんかい今回かぎり限り "this time only". The same meaning with に in front, にかぎり限り, is its own grammar point.