Semivowels.—ι, υ, the liquids, nasals, and the spirant ς are often called semivowels. (ι̯ becoming ζ, and ϝ are also called spirants.)
a. When ι and υ correspond to y and w (cp. minion, persuade) they are said to be unsyllabic; and, with a following vowel, make one syllable out of two. Semivocalic ι and υ are written ι̯ and υ̯. Initial ι̯ passed into ( (h), as in ἧπαρ liver, Lat. jecur; and into ζ in ζυγόν yoke, Lat. jugum (here it is often called the spirant yod). Initial υ̯ was written ϝ (3). Medial ι̯, υ̯ before vowels were often lost, as in τῑμά-(ι̯) ω I honour, βο(υ̯)-ός, gen. of βοῦ-ς ox, cow (43).
b. The form of many words is due to the fact that the liquids, nasals, and ς may fulfil the office of a vowel to form syllables (cp. bridle, even, pst). This is expressed by λ̣ο̣, μ̣ο̣, ν̣ο̣, ρ̣ο̣, σ̣ο̣, to be read ‘syllabic λ,’ etc., or ‘sonant λ’ (see 35 b, c).