英语词源字典 - 在线词源网站

fond [fond 词源字典]: fond: [14] Fond originally meant ‘foolish’, and the likeliest explanation of its rather problematic origin is that it was a derivative of the Middle English noun fon ‘fool’ (its Middle English spelling fonned suggests that it was formed with the suffix -ed, just as wretched was formed from wretch). However, where fon (probably a relative of modern English fun) comes from is another matter.

Links with Swedish fåne ‘fool’ have been suggested but never established for certain. The adjective’s modern meaning ‘having a great liking’, incidentally, developed in the 16th century via an intermediate ‘foolishly doting’. Fondle [17] is a back-formation from the now obsolete fondling ‘foolish person’, a derivative of fond.
=> fondle, fun[fond etymology, fond origin, 英语词源]
dote (v.): c. 1200, "to be feeble-minded from age," from Middle Low German doten "be foolish," which is of unknown origin. Meaning "to be infatuated" is from late 15c. Related: Doted; dotes; doting.