means A person with magical powers, or by extension someone with extraordinary skill at something.

from From Middle English 'wysard,' built from 'wise' plus the suffix '-ard' — the same dismissive ending you find in 'drunkard' and 'sluggard.' So a wizard was, literally, a 'wise one,' though that '-ard' carried a faint sneer, as if too much wisdom were itself a bit suspect. The magical sense bloomed later, in the 1500s; the original word just meant a sage or philosopher.