SELDOMLY
Etymology
Adverb
seldomly (comparative more seldomly, superlative most seldomly)
(rare, sometimes, proscribed) Seldom; rarely.
Usage notes
• Sometimes proscribed in favor of the more common seldom, itself an adverb.
• At COCA seldom occurs more than 5,000 times; seldomly 12. It is even rarer in the BNC.
Source: Wiktionary
SELDOM
Sel"dom, adv. [Usually, compar. More seldom (; superl. Most seldom (;
but sometimes also, Seldomer (, Seldomest.] Etym: [AS. seldan,
seldon, seldum, fr. seld rare; akin to OFries. sielden, D. zelden, G.
selten, OHG. seltan, Icel. sjaldan, Dan. sielden, Sw. sällan, Goth.
sildaleiks marvelous.]
Definition: Rarely; not often; not frequently.
Wisdom and youth are seldom joined in one. Hooker.
Sel"dom, a.
Definition: Rare; infrequent. [Archaic.] "A suppressed and seldom anger."
Jer. Taylor.
Source: Webster’s Unabridged Dictionary 1913 Edition