PASSABLY
reasonably, moderately, pretty, jolly, somewhat, fairly, middling, passably
(adverb) to certain extent or degree; “pretty big”; “pretty bad”; “jolly decent of him”; “the shoes are priced reasonably”; “he is fairly clever with computers”
Source: WordNet® 3.1
Etymology
Adverb
passably (comparative more passably, superlative most passably)
In a passable fashion, moderately; adequately.
Source: Wiktionary
Pass"a*bly, adv.
Definition: Tolerably; moderately.
PASSABLE
Pass"a*ble, a. Etym: [Cf. F. passable.]
1. Capable of being passed, traveled, navigated, traversed,
penetrated, or the like; as, the roads are not passable; the stream
is passablein boats.
His body's a passable carcass if it be not hurt; it is a throughfare
for steel. Shak.
2. Capable of being freely circulated or disseminated; acceptable;
generally receivable; current.
With men as with false money -- one piece is more or less passable
than another. L'Estrange.
Could they have made this slander passable. Collier.
3. Such as may be allowed to pass without serious objection;
tolerable; admissable; moderate; mediocre.
My version will appear a passable beauty when the original muse is
absent. Dryden.
Source: Webster’s Unabridged Dictionary 1913 Edition