Lexical Definition

‎ἀδημονέω‎ adēmonéō (ad-ay-mon-eh'-o) be distressed G:V
from a derivative of (to be sated to loathing)

be full of heaviness, be very heavy.

Usage: 2 forms in 3 verses
Form Translated As     In Verse(s)
ἀδημονῶν being deeply distressed Phil.2.26
ἀδημονεῖν to be deeply distressed Matt.26.37Mark.14.33

Abbott-Smith

** ἀδημονέω, -ῶ (on the derivation, v. MM, VGT, s.v.), [in Aq.: Jb 18:20; Sm.: Ps 60 (61):3* 115:2* (116:11), Ec 7:17(16), Ez 3:15*;]
to be troubled, distressed (MM, l.c.): Mt 26:37, Mk 14:33, Phl 2:26.†

Abbott-Smith References

Book Refs
Job 18:20
Psalms 61:3* · 115:2* · 116:11
Ecclesiastes 7:16 · 7:17
Ezekiel 3:15
Matthew 26:37
Mark 14:33
Philippians 2:26

Liddell-Scott-Jones

ἀδημονέω,

to be sorely troubled or dismayed, be in anguish, [Refs 5th c.BC+]; ὑπό τινος to be puzzled by.., [Refs 4th c.BC+], which is found only as variant in [Refs 5th c.BC+]