Lexical Definition

‎ὀνικός‎ onikós (on-ik-os') huge millstone ^G:A
from ‎ὄνος‎

millstone.

• belonging to a ass, i.e. large (so as to be turned by a ass)

Abbott-Smith

*† ὀνικός, -ή, -όν (< ὄνος),
of or for an ass: μύλος ὀ., Mt 18:6, Mk 9:42 (elsewhere only in π.; v. MM, xviii).†

Abbott-Smith References

Liddell-Scott-Jones

ὀνικός-ῐκός, ή, όν,

of or for an ass: μύλος ὀ., see at {μύλος}; ὀ. κτήνη, i. e. asses, [Refs 1st c.AD+]; γόμος ὀ. [Refs 2nd c.AD+]