The Bedford Glossary of Critical and Literary Terms - Ross Murfin 2018
Long meter (long measure)
Long meter (long measure): A four-line stanza typically written in iambic tetrameter with an abab or abcb rhyme scheme. Long meter, often abbreviated “L.M.,” is often used in hymns.
EXAMPLE: The first stanza of the hymn “O God, Beneath Thy Guiding Hand” (1793):
Ŏ Gód,│bĕneáth│thy̆ guі́d│in̆g hánd
Our exiled parents crossed the sea
And when they trod the wintry strand,
With prayer and psalm they worshiped thee.