Strong's G4615 · Greek

σίναπι

sinapi · sin'-ap-ee

perhaps from sinomai (to hurt, i.e. sting); mustard (the plant)

Scholarly Lexicons

Abbott-Smith Manual Greek Lexicon

 5 † σίναπι , -εως, τό (prob. Egyptian), = Attic τὸ νᾶπυ mustard : Mt 13:31 17:20 , Mk 4:31 , Lk 13:19 17:6 .† 

G. Abbott-Smith, A Manual Greek Lexicon of the New Testament (1922) — public domain