Source : Webster's Revised Unabridged Dictionary (1913)

Seldem \Sel"dem\, adv. [Usually, Compar. {More seldom}; superl.
   {Most seldom}; but sometimes also, {Seldomer}, {Seldomest}.]
   [AS. seldan, seldon, seldum, fr. seld rare; akin to OFries.
   sielden, D. zelden, G. selten, OHG. seltan, Icel. sjaldan,
   Dan. sielden, Sw. s["a]llan, Goth. sildaleiks marvelous.]
   Rarely; not often; not frequently.

         Wisdom and youth are seldom joined in one. --Hooker.