Heptameter

Heptameter is one or more lines of verse containing seven metrical feet (usually fourteen or twenty-one syllables).

An example from Lord Byron's Youth and Age:

'Tis but as ivy-leaves around the ruin'd turret wreathe,

All green and wildly fresh without, but worn and gray beneath.

O could I feel as I have felt, or be what I have been,

Or weep as I could once have wept o'er many a vanish'd scene,-

As springs in deserts found seem sweet, all brackish though they be,

So midst the wither'd waste of life, those tears would flow to me!