1580s, of an animal, "fondled and indulged," from pet (n.1). Of a thing, material or immaterial, "favored, favorite," by 1826.
1670s, "a branching out, a structure like or analogous to the branches of a tree," from French ramification, from ramifier (see ramify). Transferred sense of "outgrowth, consequence," in reference to immaterial things, is attested by 1755. Related: Ramifications.
1852, "move by means of a ratchet," from ratchet (n.). Transferred sense "cause something (immaterial) to move (up or down) in jerky increments, as if by ratchet" is attested by 1977. Related: Ratcheted; ratcheting.