English

extracostal

From extra- + costal.

Proto-Indo-European *h₁éǵʰs ‘out’

Proto-Indo-European *h₁eǵʰsteros

Proto-Italic *eksteros

Latin exter ‘being on the outside’

Latin extrā ‘outside, except, beyond’

Latin costa ‘rib’

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

French costal

Today it means

adj Outside of the ribs.

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

Etymograph / extracostal