2. Adjective. (rail transport of a train) to have a locomotive at each end ¹
3. Adjective. (rail transport of a multiple unit) to have a driving cab at each end ¹
4. Adjective. (rail transport of a train or multiple unit) to have a driver at each end ¹
5. Verb. (past of double-end) ¹
¹ Source: wiktionary.com