1) Type of verse 2) Verse 3) Verse line 
Decasyllable (Italian: decasillabo, French: décasyllabe) is a poetic meter of ten syllables used in poetic traditions of syllabic verse. In languages with a stress accent (accentual verse), it is the equivalent of pentameter with iambs or trochees (particularly iambic pentameter). Decasyllable was used in epic poetry of the Southern Slavs (for ex...
[n] - a verse line having ten syllables
decasyllable Related 'metric' families: yotta; zetta; exa; peta; tera; giga; mega; kilo; hecto; deci; centi; milli; micro; nano; pico; femto; atto; zepto; yocto.
noun a verse line having ten syllables
a word or line of verse of ten syllables.