(TA, and so in a copy of the S,) and ↓دَيءِبٌ (TA, and so in two copies of the S,) Striving, labouring, toiling, or exerting himself, and wearying himself, in his work [&c.: or holding on, or continuing, therein: see the verb]. (S, TA.)
2.
[Hence,] لَيْلَةٌ دَايءِبَةٌ [A hard, fatiguing, or continuous, night-journey]. (M and K in article مرس.)
3.
And الدَّايءِبَانِ (tropical:) The night and the day; (S, A, K;) which [are so called because they] hold on their course (يَدْأَبَانِ) in their alternating. (TA.)