verb

• (metallurgy) To subject to great heat and then (often slow) cooling, and sometimes reheating and further cooling, for the purpose of rendering less brittle; to temper; to toughen.
  "The best tough soft iron, such as will weld round, is drawn into rods by smiths, using charcoal fires, and taking welding heats every time, the rod is about 1.4 inch diameter, 9 or 10 feet long, containing 4lbs. each, tapered at each end to a long point; they are first anealed by being brought to a bright red heat, in a furnace excluding the air as much as possible, for if the air can be entirely excluded, no scab will rise in anealing; […]"
• (archaic) To burn colors onto a glass or other surface.
  "It was customary to beautify the Prow with Gold, and various ſorts of Paint and Colours: […] Several other Colours were alſo made uſe of, nor were they barely varniſh'd over with them, but very often anneal'd by Wax melted in the Fire, ſo as neither the Sun, Winds, or Water were able to deface them."
• (genetics, ambitransitive) To make a double-stranded nucleic acid by pairing a single strand with a complementary strand.
  "The 5′ junction is checked using a target gene-specific primer of ~21 nucleotides, which anneals upstream of the cassette integration site, together with a primer which anneals downstream of the first loxP site in the PCR cassette."
• (figurative, archaic or poetic) To strengthen or harden.
  "The experience annealed them, strengthening their resolve."

noun

• (chemistry, metallurgy) An act of annealing.
  "Additional information obtained from counting krypton-85 released during the anneals shows that only fractions of a per cent of the theoretical amount of gas are released […]"