Legnaderk is bounded on the north by Aghnacollia and Commas (Kinawley) townlands, on the west by Bellavally Upper townland, on the east by Altachullion Lower and Altachullion Upper townlands and on the south by Altnadarragh townland. It is part of the Cuilcagh mountain range and its chief geographical features are Benbeg Mountain (An Bhinn Bheag meaning ‘The Small Peak'), which reaches a height of 539 metres, mountain streams, waterfalls, forestry plantations and a spring well. The townland is traversed by the regional R200 road (Ireland), minor public roads and rural lanes. The townland covers 357 statute acres.