Relating to or characteristic of costume or costumes.
From 'costume' plus the suffix '-ic' (relating to). This learned adjective is primarily found in specialized theatrical and academic contexts rather than everyday English.
While 'costumey' is informal and often critical, 'costumic' is the scholarly way to say something is related to costumes. You'd see it in academic papers about theater history, not in casual conversation.
Complete word intelligence in one call. Free tier — 50 lookups/day.