けらば

Etymology
Compound of, possibly from a similarity between the wings of certain mole crickets and the way the eaves on a gabled roof come together at the peak of the gable, possibly also from a resemblance between the veins of the wing and the beams of a gable roof.

First cited to the edition dated to 1177–81.

Noun

 * 1)   the eaves of a gable roof above the triangular gable wall: the verge

Usage notes
The kana spellings or  appear to be more common than the kanji spellings  or, likely due to the rarity and complexity of the kanji used to spell the  portion.