κεραύνιον
From LSJ
English (LSJ)
τό,
A truffle, Tuber aestivum, Thphr.HP1.6.5, Gal.19.731. II critical mark to indicate corrupt passages, Isid.Etym.1.21.21, Sch.Il.ip.xliii Dind.; but πρὸς τὴν ἀγωγὴν τῆς φιλοσοφίας D.L.3.66. III = κεραυνία λίθος, PHolm.5.40, Isid.Etym.16.13.5, etc.