Sources

Deghmethe 1336-7 Bain’s Cal vol. 3, p. 378
Dechmete c. 1340 Bann Cl. 94
Dechment 1381-2 Bann. Cl.

Early forms sourced from MacDonald 77-78.

‘Good, excellent hill,’ MacDonald, 78

“The first part was probably O.W. dug, now da, good, displaced by O.Ir. dag– deg-, now deagh, good; compare the hill Deagh-choimhead, ‘good prospect,’ in Muckairn parish, Argyll. In the second part –methe of 1337 is doubtless for –menthe, with which may be compared Meneted, for Menet-ted, Menteith.”  Watson 1926, 400 [in discussion of names containing monadh]