the adverb 'tolerably' is built upon the latin verb tolerare, which means 'to bear' or 'to endure'. this root passed into english via the adjective 'tolerable', formed by adding the suffix '-able' to denote something capable of being endured. the final addition of the adverbial suffix '-ly' transforms it into a word describing the manner of an action. thus, the literal sense of 'in a manner capable of being endured' evolved into its modern meanings of 'to an acceptable degree' or 'fairly well', capturing the idea of something being just good enough to bear.

Structure: toler (endure) + able (capable of) + ly (adverb suffix) toler (from latin tolerare, meaning 'to bear, endure'), able (from latin -abilis, an adjective-forming suffix meaning 'capable of, fit for'), ly (from old english -lice, an adverb-forming suffix).