Gwylnos, n. a wake night
Gwylnosi, v. to keep vigils
Gwylo, v. to be bashful; to weep
Gwylog, n. the guillemot
Gwylys, n. the licorice plant
Gwyll, a. gloom, darkness
Gwyll, a. gloomy, dark, dusky
Gwylledd, n. gloom
Gwyllion, n. shades; goblins
Gwyllt, n. a wild, wilderness