The headword, evidently extracted from the quotation given, is accusative singular of lea/nteira.
[1] Greek Anthology 6.295.5 (Phanias); cf. sigma 953 and psi 36. On this epigram, wherein a scribe dedicates his professional tools to the Muses after his promotion, see Gow and Page (vol. I, 162), (vol. II, 467-469), and another excerpt at sigma 214. As Gow and Page note (vol. II, 468), J.F. Dübner (German classical scholar, naturalized French, 1802-1867) suggested that the compass was used to draw circles; cf. Paton's translation (456-459). However, Gow and Page argue that a scribe would typically use the karki/nos as a divider in order to equally space lines on a page; cf. Gardthausen (184-185).