Y Lliwedd is a Hewitt of 897.9 m in Gwynedd. Its drop clears the 150 m Marilyn standard by only 3.8 m.
Only seven of the register's Wales hills are higher. It sits below Snowdon – Yr Wyddfa, only 1.6 km to the north-west and 187.1 m higher. The higher hill nearest to it, Snowdon – Yr Wyddfa, is a 3,000 ft mountain, 1.6 km to the north-west. The key col is close by, only 0.5 km to the north-west at 744.1 m. The highest point is recorded as rock, not a cairn.