also tom-fool, "buffoon, clown," 1640s, from Middle English Thom Foole, personification of a mentally deficient man (mid-14c.), see Tom + fool (n.).
-ery
word-forming element making nouns meaning "place for, art of, condition of, quantity of," from Middle English -erie, from Latin -arius (see -ary). Also sometimes in modern colloquial use "the collectivity of" or "an example of."