among the Greeks, was a long portico, open or covered at the top, where the athletes practised wrestling and running: the gladiators, who practised therein, were called xystici. Among the Romans, the xylius was only an alley, or double row of trees, meeting like an arbour, and forming a shade to walk under. Y.

Y, or y, the 23d letter of our alphabet: its sound is formed by expelling the breath with a sudden expansion of the lips from that configuration by which we express the vowel u. It is one of the ambigential letters, being a consonant in the beginning of words, and placed before all vowels, as in yard, yield, young, &c. but before no consonant. At the end of words it is a vowel, and is substituted for the sound of i, as in try, defery, &c. In the middle of words it is not used so frequently as i is, unless in words derived from the Greek, as in chyle, empyreal, &c. though it is admitted into the middle of some pure English words, as in dying, flying, &c. The Romans had no capital of this letter, but used the small one in the middle and last syllables of words, as in corymbous, onyx, martyr. Y is also a numeral, signifying 150, or, according to Baroniuss, 159; and with a dash a-top, as \( \overline{Y} \), it signified 150,000.