The Collaborative International Dictionary of English v.0.48:

Caldron \Cal"dron\ (k[add]l"dr[u^]n), n. [OE. caldron, caudron,
   caudroun, OF. caudron, chauderon, F. chaudron, an aug. of F.
   chaudi[`e]re, LL. caldaria, fr. L. caldarius suitable for
   warming, fr. caldus, calidus, warm, fr. calere to be warm;
   cf. Skr. [,c]r[=a] to boil. Cf. Chaldron, Calaric,
   Caudle.]
   A large kettle or boiler of copper, brass, or iron. [Written
   also cauldron.] "Caldrons of boiling oil." --Prescott.
   [1913 Webster]

WordNet (r) 3.0 (2006):

caldron
    n 1: a very large pot that is used for boiling [syn: caldron,
         cauldron]