prefix
faintly; dimly; slightly; barely
Prefix attached to adjectives and verbs to indicate a faint, slight, or barely perceptible degree. Common in literary or poetic contexts. Used in fixed expressions like ほの白い (faintly white) and ほの見える (dimly visible).
東の空がほの白くなってきた。
The eastern sky has become faintly light.
霧の向こうに灯りがほの見える。
A light is dimly visible beyond the fog.
かすかに is a standalone adverb meaning 'faintly' or 'dimly', while ほの is a prefix that attaches to other words to convey a similar nuance.
The prefix ほの is of native Japanese origin, likely related to the adjective ほのか (faint, dim). The exact derivation is uncertain.