Lexical Definition

‎ἱλαρός‎ hilarós (hil-ar-os') cheerful G:A
from the same as ‎ἵλεως‎

cheerful.

Usage: 2 forms in 3 verses
Form Translated As     In Verse(s)
ἱλαρὸν a cheerful 2Cor.9.7
ιλαρόν A happy LXX.Prov.22.8
his happy LXX.Prov.19.12

Abbott-Smith

ἱλαρός, -ά, -όν (< ἵλαος = ἵλεως, q.v.), [in LXX: Pr 19:12 (רָצוֹן) 22:8, Es 5:1, Jb 33:26, Si 13:26 26:4, III Mac 6:35*;]
cheerful, joyous: II Co 9:7 (Pr 22:8(9)(LXX)).†

Abbott-Smith References

Book Refs
Ezra 5:1
Job 33:26
Proverbs 19:12 · 22:8 · 22:9
2 Corinthians 9:7

Liddell-Scott-Jones

ἱλαρός [], , όν,

(ἵλαος) cheerful, merry, φέγγος [NT+5th c.BC+], gracious, [Refs 4th c.BC+]; -ωτέρα ἀγγελία more cheerful news, [Refs]. adverb -ρῶς[LXX+5th c.BC+]

__II of blood, quick-pulsing, [Refs 2nd c.AD+]
__III of imitation gold, bright, [Refs 3rd c.AD+] adverb ἱλαρῶς (to be read ἱλαρῷ)[Refs]

LSJ Scripture Refs: 2Cor.9.7LXX.Prov.22.8LXX.Job.22.26