anneal comes from Middle English anelen, from Old English onaelan ('to set on fire, kindle'), from on- ('on') + aelan ('to burn, bake'), from al ('fire, burning'). Morphologically, the word is transparent as a compound: its parts remain visible in the modern spelling, while the older history of those parts supplies the deeper ancestry. In modern use, the verb sense is "to heat metal or glass and cool it slowly to toughen and reduce brittleness", which keeps the etymology connected to the word's present dictionary value rather than treating it as a merely historical label. The wider word family includes derivatives such as annealer, annealing, showing how the same base continues to support neighboring English vocabulary. The principal historical forms in the chain include Old English onaelan, Old English aelan, which anchor the explanation in named linguistic material.