Drtno was attested in written sources as Odertnim in 1571, and in older modern sources it was spelled Dertno. The name is probably derived from Slavic 'cleared field', referring to land that was cleared for farming. Related toponyms include Drtija and Razdrto, as well as various microtoponyms.
History
Drtno had a population of nine in 1900, six in 1931, and nine in 1953. It has no residents today. Drtno was annexed by Hribi in 1953, ending its existence as a separate settlement.