に足(た)りないTo not be worthy, To not be enough, To not be sufficient, To lack

に足(た)りない is a grammar expression appearing after the dictionary form of verbs used to indicate that something is 'not worth (A)', or 'not sufficient for (A)'. It comes from a combination of the case-marking particle に, and the る-Verb 足(た)りる 'to be sufficient', or 'to be enough'.

This structure is formal, so will mostly be used in literature or formal speech settings.

While に足(た)りない may be similar to another grammar point, に足(た)る, in that they are conversely pointing out the worth, or lack of worth of something, they are actually different verbs. 足(た)る is an う-Verb, and is often used more in literature, or in western Japan. This means that the negative form of 足(た)る is 足(た)らない, not 足(た)りない.

Caution

Both 足(た)りない and 足(た)らない may be used as part of the set phrase 取(と)るに足(た)りない, 'to be worthless', or 'to not be worth taking up for discussion'.