core + attic (Attic Area): these terms have been either deprecated from the core or extentions, or removed from pending as not accepted into the full vocabulary.

thumbnailUrl

Canonical URL: http://schema.org/thumbnailUrl

Thing > Property > thumbnailUrl

A thumbnail image relevant to the Thing.

Usage: Between 500,000 and 1,000,000 domains
Values expected to be one of these types
URL
Used on these types
CreativeWork

Schema Version 3.3