ゆ adverb

ゆいいつの（唯一）: sole ~, only ~
ゆえに（故に）: on account of, because of, since; consequently, therefore
ゆかいな（愉快）: pleasant, happy, having a good time
ゆたかな（豊かな）: abundant, plentiful; rich
ゆっくり: slowly
ゆったりと: loose, relaxed, calm, comfortable
ゆうゆうと（悠々）: calmly, with composure, comfortably
ゆめゆめ: never, under no circumstances
ゆらめく（揺めく）: shake, tremble, waver, sway
ゆらゆらと: waving, swaying, flickering
ゆるやかに（緩やか）: gently; gentle, lenient, loose, easy
ゆるりと（緩り）: feel at home, take it easy, in a relaxed way