Abbott-Smith Manual Greek Lexicon
πικραίνω (G4087)
4 πικραίνω ( πικρός ), [in LXX for מרר , קצף , etc.;] to make bitter : Re 10:9 ; pass., Re 8:11 10:10 ; metaph., to embitter (LXX): pass., seq. πρός , Col 3:19 .†
G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922) — public domain