U ( oo ) - v úll.

uacht - v audacht.

uaimh - cave, crypt.

Uaithne - Harp of the Dagda (v cruit).

uarán - spring (water).

uasal - noble (person of either gender).

uath - 1) hawthorn, fiodh for the letter H, associated with, among other things, trial, quest; 2) as prefix: spontaneous.

uathrosc - spontaneous rosc.

údarás - (esp. self-assumed or unofficially acknowledged, but valid) authority.

Uisneach - hill S.W. of Teamhair, ceremonial meeting of the five provinces.

Uladh - Ulster.

úll - apple, fiodh for the letter U, associated with, among other things, happiness, love.

upa - folk-charm (physical object).

upthaireacht - folk magic.

upthóg - folk magic practitioner.

urchar (-air) - "fairy dart", a sudden physical pain or dysfunction sent by the Sídhe.

urnaidhm - 1) harp string-pin; 2) pledge.