English

intracostal

From intra- + costal.

Proto-Indo-European *h₁én ‘in’

Proto-Indo-European *h₁énteros ‘inside, within’

Latin *interus

Latin intrā ‘within’

Latin costa ‘rib’

Medieval Latin costālis ‘Of, pertaining to or resembling ribs’

French costal

Today it means

adj Within a rib.

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

Etymograph / intracostal