considerable (adj.)

mid-15c., "capable of being considered, conceivable," from Medieval Latin considerabilis "worthy to be considered," from Latin considerare "to look at closely, observe," probably literally "to observe the stars," from assimilated form of com "with, together" (see con-) + sidus (genitive sideris) "heavenly body, star, constellation" (see sidereal).

Meaning "pretty large" is from 1650s (implied in considerably), from now-archaic earlier sense of "Worthy of regard or attention" (1610s).

CONSIDERABLE. This word is still frequently used in the manner pointed out by Dr. Witherspoon in the following remark: "He is considerable of a surveyor; considerable of it may be found in the country. This manner of speaking prevails in the northern parts." [Pickering, "A Vocabulary, or Collection of Words and Phrases Which Have Been Supposed to be Peculiar to the United States of America," 1816]

updated on August 20, 2020

Definitions of considerable from WordNet

considerable (adj.)
large or relatively large in number or amount or extent or degree;
spent a considerable amount of time on the problem
the economy was a considerable issue in the campaign
went to considerable trouble for us
a considerable quantity
Etymologies are not definitions. From, not affiliated with etymonline.