U sometimes borrows the sound of some other vowel; for bury is pronounced berry, and busy is pronounced bizzy. So in the derivatives, burial, buried, busied, busily, and the like.
The long or diphthongal u, commonly sounded as yu, or as ew in ewer,—or any equivalent diphthong or digraph, as ue, ui, eu, or ew.—when it follows r or rh, assumes the sound of slender o or oo; as in rude, rhubarb, rue, rueful, rheum, fruit, truth, brewer.
DIPHTHONGS BEGINNING WITH U.
U, in the proper diphthongs, ua, ue, ui, uo, uy, has the sound of w or of oo feeble; as in persuade, query, quell, quiet, languid, quote, obloquy.
Ua, an improper diphthong, has the sound—1. Of middle a; as in guard, guardian. 2. Of close a; as in guarantee, piquant. 3. Of obscure e; as in victuals and its compounds or kindred. 4. Of open u; as in mantuamaker.
Ue, an improper diphthong, has the sound—1. Of open u; as in blue, ensue, ague. 2. Of close e; as in guest, guesser. 3. Of close u; as in leaguer. Ue final is sometimes silent; as in league, antique. Ui, an improper diphthong, has the sound—1. Of open i; as in guide, guile. 2. Of close i; as in conduit, circuit. 3. Of open u; as in juice, sluice, suit.
Uo can scarcely be called an improper diphthong, except, perhaps, after q in liquor, liquorice, liquorish, where uor is heard as ur.
Uy, an improper diphthong, has the sound—1. Of open y; as in buy, buyer. 2. Of feeble y, or of ee feeble; as in plaguy, roguy.
TRIPHTHONGS BEGINNING WITH U.
Uai is pronounced nearly, if not exactly, like way; as in guai-a-cum, quail, quaint. Uaw is sounded like wa in water; as in squaw, a female Indian. Uay has the sound of way; as in Par-a-guay: except in quay, which nearly all our orthoepists pronounce kee. Uea and uee are each sounded wee; as in queasy, queer, squeal, squeeze. Uoi and woy are each sounded woi; as in quoit, buoy. Some say, that, as u, in these combinations, sounds like w, it is a consonant; others allege, that w itself has only the sound of oo, and is therefore in all cases a vowel. U has, certainly, in these connexions, as much of the sound of oo, as has w; and perhaps a little more.