ateorian

By surface analysis, ā- +‎ teorian.

āteorian

1. to fail

   Woruldlīċe ǣhta āteoriaþ, ac sōþ ġelēafa belīfþ ā.

   Worldly possessions fail, but true belief always survives.

2. to become tired or weary

   Þæt wīf āteorode for þām þe hēo tō lange wacode.

   The woman grew tired because she had been awake for too long.

3. to cease, leave off
4. to lack, be wanting

   Ne āteoraþ ūs nǣfre nān hungriġ mūþ tō fēdenne.

   We will never want for a hungry mouth to feed (literally "To us, a hungry mouth to feed is never lacking").

5. (by extension, of grammar) to be defective

   Þæt word bēon āteoraþ on Englisċ, for þām þe hit nāne forþġewitene tīde næfþ.

   The verb "bēon" is defective in Old English, because it doesn't have a past tense.