Than
Old English than(ne), thon(ne), thænne, originally the same word as then.
wiktionary
From Middle English than, thanne, from Old English þanne, a variant of þonne(“then, since, because”), from Proto-Germanic *þan(“at that, at that time, then”), from earlier *þam, from Proto-Indo-European *tóm, accusative masculine of *só(“demonstrative pronoun, that”). Cognate with Dutch dan(“than”), German denn(“than”), German dann(“then”). Doublet of then.
etymonline
than (conj.)
Old English þan, conjunctive particle used after a comparative adjective or adverb, from þanne, þænne, þonne "then" (see then). Developed from the adverb then, and not distinguished from it by spelling until c. 1700.
The earliest use is in West Germanic comparative forms introducing the second member, i.e. bigger than (compare Dutch dan, German denn), which suggests a semantic development from the demonstrative sense of then: A is bigger than B, evolving from A is bigger, then ("after that") B. Or the word may trace to Old English þonne "when, when as," such as "When as" B is big, A is more (so).
