Definition of oblongly in US English:

oblongly

adverb

Botany
rare
  • So as to form an oblong; with an elongated form in the manner of an oblong.

Origin

Mid 17th century; earliest use found in John Bulwer (bap. 1606, d. 1656), medical practitioner and writer on deafness and on gesture. From oblong + -ly.

Pronunciation

oblongly

/ˈɒblɒŋli/