Once more English has complicated something that didn't need to be complicated. The four-letter verb for the process "to accustom (a young child or animal) to take food otherwise than by nursing" is wean. But what about the noun form? Is it something as simple as the four-letter verb? No, no, dear pursuers of meaning. The noun for the act of weaning is ablactation. One-syllable verb versus a four-syllable noun that doesn't even look like the verb. That would make a good spelling bee word.