Attaches to a number or amount to mean 'less than that amount'. Often used with counters or quantities.
The meeting ended in less than an hour.
It was a purchase of under 1,000 yen.
Attaches to a noun to express that something is lacking or insufficient in that quality. Often used in set phrases like 注意足らず (insufficient attention) or 勉強足らず (insufficient study).
His failure was due to insufficient attention.
I failed the exam because of insufficient study.
insufficient syllables in waka or haiku
a little too short; slightly short · slightly inferior; a bit worse
premature birth; preterm birth
unclear speech; poor enunciation; garbled speech · poorly expressed; unclear wording; inadequate explanation
inarticulate; not saying enough; lack of words
Derived from the negative form of the verb 足る (たる, 'to be sufficient'), meaning 'not reaching' or 'not enough'. The suffix usage developed from this negative meaning.