Etimology
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.
conjunction
than
Used in comparisons, to introduce the basis of comparison.
(obsolete outside dialects, usually used with for) Because; for.
Examples
Whether modern, industrial man is less or more warlike than his hunter-gatherer ancestors is impossible to determine. The machine gun is so much more lethal than the bow and arrow that comparisons are meaningless.
Answer me if you can, any other way, than because the Scriptures, which are infallible, Say so.
she's taller than I am; she found his advice more witty than helpful; we have less work today than we had yesterday; We had no choice than to return home
If thou say yes, then puttest thou on Christ unkunning, unpower, or euil will: for than he could not make his rule so good as an other did his.
You shall also take the fine earth or mould which is found in the hollow of old Willow trees, rising from the root almost to the middle of the Tree, at least so far as the tree is hollow, for than this, there is no earth or mould finer or richer.
preposition
than
introduces a comparison, and is associated with comparatives, and with words such as more, less, and fewer. Typically, it seeks to measure the force of an adjective or similar description between two predicates.
Examples
Patients diagnosed more recently are probably surviving an average of longer than two years.
No player is more skillful than Greg.
adverb
than (not comparable)
(now chiefly dialectal or a misspelling) At that time; then.