To cover or smear with tallow, which is hard fat rendered from cattle or sheep used to make candles and soap.
From 'be-' (prefix making the action intensive) + 'tallow' (from Middle English and Old English 'talogh,' possibly from Scandinavian languages). The word emerged as people worked extensively with rendered animal fats in pre-industrial times.
Before electricity and petroleum, tallow was essential—'betallowed' hands and clothes were the occupational marks of chandlers and soap-makers, so this word literally describes the grimy reality of medieval and early-modern manufacturing.
Complete word intelligence in one call. Free tier — 50 lookups/day.