likely (adj.)

c. 1300, "having the appearance of truth or fact," perhaps from Old Norse likligr "likely," from likr "like" (see like (adj.)). Old English had cognate geliclic. Meaning "having the appearance of being strong and capable" is from mid-15c., though now mostly confined to American English; according to OED this sense is perhaps influenced by like (v.). Sense of "good-looking" ("such as may be liked") is from late 15c. Meaning "probable" is attested from late 14c., but said by OED to be now principally in American English. As an adverb, late 14c., from the adjective.

LIKELY. That may be liked; that may please; handsome. In the United States, as a colloquial term, respectable; worthy of esteem; sensible.—Worcester. [Bartlett]

updated on August 16, 2020

Definitions of likely from WordNet
likely (adj.)
has a good chance of being the case or of coming about;
a likely place for a restaurant
these services are likely to be available to us all before long
likely candidates for the job
rain is likely
she is likely to forget
the broken limb is likely to fall
a likely topic for investigation
likely (adj.)
expected to become or be; in prospect;
Synonyms: potential
likely (adj.)
within the realm of credibility;
not a very likely excuse
likely (adj.)
likely but not certain to be or become true or real;
a likely result
Synonyms: probable
likely (adv.)
with considerable certainty; without much doubt;
Synonyms: probably / in all likelihood / in all probability / belike
Etymologies are not definitions. From, not affiliated with etymonline.