þéostrian

Part of speech: verb
Verb type: weak verb (2)
1. 1) to make dark/dim; 2) to grow dark, become dim; 2. to deteriorate, fail (said of somebody's eyesight) (also þíestrian, þýstrian, þístrian, ðéostrian, ðíestrian, ðýstrian)
Etymology
[← þéostor a “dark, gloomy”]
Paradigm

4.2.2. - 2nd class weak verbs

The second class of the weak verbs is marked by the presence of the Prot-Germ suffix *-ō-, preserved in the Anglo-Saxon in the form of short vowel -o- of the past tense suffix: macode (made); lufode (loved), etc.

II class infinitive past tense singular
to look (at); to see lócian, lóciȝan lócode
to love lufian lufode