Stanza = a set amount of lines in poetry grouped together by their length, meter or rhyme scheme.
Couplet = a two-line stanza.
Tercet = a three-line stanza.
Quatrain = a four-line stanza.
Cinquain = a five-line stanza.
Sestet = a six-line stanza.
Meter = the pattern of stressed syllables (long-sounding) and unstressed syllables (short-sounding) in poetry.
Rhyme scheme = the pattern of rhyme that comes at the end of each line or verse.
Syllable = the single, unbroken sound of a spoken or written word.