The Collaborative International Dictionary of English v.0.48:

Seldom \Sel"dom\ (s[e^]l"d[u^]m), adv. [Usually, Compar. More
   seldom (m[=o]r" s[e^]l"d[u^]m); superl. Most seldom
   (m[=o]st" s[e^]l"d[u^]m); but sometimes also, Seldomer
   (s[e^]l"d[u^]m*[~e]r), Seldomest.] [AS. seldan, seldon,
   seldum, fr. seld rare; akin to OFries. sielden, D. zelden, G.
   selten, OHG. seltan, Icel. sjaldan, Dan. sielden, Sw.
   s[aum]llan, Goth. sildaleiks marvelous.]
   Rarely; not often; not frequently.
   [1913 Webster]

         Wisdom and youth are seldom joined in one. --Hooker.
   [1913 Webster]