English

interest-free

From interest + -free.

Formed from interest + -free

Proto-Indo-European *h₁es- ‘to be’

…

Latin intersum ‘to be between; to concern’

Medieval Latin intersum ‘to concern’

Old French interesse

Middle English interest

Today it means

adj Not charging interest; not subject to interest payments.

Language periods are conventional ranges, not dates for this word.

Etymograph / interest-free