Usage: 3 forms in 10 verses
Form Translated As     In Verse(s)
φακόσ flask LXX.1Sam.26.16
φακόν flask LXX.1Sam.10.1LXX.1Sam.26.11LXX.1Sam.26.12LXX.2Kgs.9.1LXX.2Kgs.9.3
lentils LXX.2Sam.17.28LXX.Ezek.4.9
φακού of lentils LXX.Gen.25.34LXX.2Sam.23.11

Liddell-Scott-Jones

φακός (phakos) a flask G:N-M

φακός,

(φακόν, τό, Papyrus in [Refs], lentil, Ervum Lens, and its fruit, Solon 38.3, [LXX+5th c.BC+]

__b plural ={φακῆ}, lentil-soup, [Refs 5th c.BC+]
__2 φ. ἐπὶ τῶν τελμάτων, duckweed, Lemna minor, [Refs 1st c.AD+]
__II anything shaped like lentils:
__II.1 hot-water bottle, [Refs 1st c.AD+]; φ. ὀστράκινος [Refs 5th c.BC+]oil-flask, [LXX]
__II.2 spot on the body, mole, birthmark, [Refs 3rd c.BC+]
__II.3 ornament on beds, Theodor.Hierap. cited in [Refs 2nd c.AD+]. (Cf. Albanian baθε 'Vicia Faba'.)

LSJ Scripture Refs: LXX.Gen.25.34LXX.1Kgs.10.1