This is just a quick reminder (of what I covered briefly in March 2012) that intrā gives rise to one of the few comparative / superlative adjectival pairs that is not derived from an adjective.
- intrā, within —> interior, -ōris, inner —> intimus, a, -um inmost
A&G offer this fascinating footnote:
“The forms in -trā and -terus were originally comparative (cf. alter), so that the comparatives in -terior are double comparatives.” (my emphasis)
- Like this: in + accusative —> intrā + accusative —> interior, -ōris
The Essential AG: 130a