y, the twenty-fifth letter of the english alphabet, at the beginning of a word or syllable, except when a prefix (see y-), is usually a fricative vocal consonant; as a prefix, and usually in the middle or at the end of a syllable, it is a vowel.  see guide to pronunciation, // 145, 178-9, 272.-something shaped like the letter y; a forked piece resembling in form the letter y.-one of the forked holders for supporting the telescope of a leveling instrument, or the axis of a theodolite; a wye.-a forked or bifurcated pipe fitting.-a portion of track consisting of two diverging tracks connected by a cross track.-i.