The Collaborative International Dictionary of English v.0.48:

Tael \Tael\, n. [Malay ta[i^]l, a certain weight, probably fr.
   Hind. tola, Skr. tul[=a] a balance, weight, tul to weigh.]
   A denomination of money, in China, worth nearly six shillings
   sterling, or about a dollar and forty cents; also, a weight
   of one ounce and a third. [Written also tale.]
   [1913 Webster] Taen

WordNet (r) 3.0 (2006):

tael
    n 1: a unit of weight used in east Asia approximately equal to
         1.3 ounces