pond: [13] Pond is historically the same word as pound ‘enclosure’. The differentiation between the two was established early on, although pound continued to be used for ‘pond’ in Scotland and in some English dialects until quite recently. The common denominator is that ponds were originally specifically used for keeping fish in. The reason for the phonetic change from pound to pond is not known. => pound
c. 1300 (mid-13c. in compounds), "artificially banked body of water," variant of pound "enclosed place" (see pound (n.2)). Applied locally to natural pools and small lakes from late 15c. Jocular reference to "the Atlantic Ocean" dates from 1640s. Pond scum (Spirogyra) is from 1864 (also called frog-spittle and brook-silk. As figurative for "someone extremely repulsive," from 1984.
