Etymology
Advertisement
or (conj.)

c. 1200, "either, else, otherwise, as an alternative or substitute," from Old English conjunction oþþe "either, or," which is related to Old Frisian ieftha, Middle Dutch ofte, Old Norse eða, Old High German odar, German oder, Gothic aiþþau "or."

This word was extended in early Middle English (and Old High German) with an -r ending, perhaps by analogy with "choice between alternative" words that ended thus (such as either, whether); then it was reduced to oþþr, at first in unstressed positions (commonly thus in Northern and Midlands English by 1300), and finally to or, though other survived in this sense until 16c.

Compare either, which is originally the same word. The contraction took place in the second term of an alternative, such as either ... or, descended from a common construction in Old English, where both words originally were oþþe (see nor). Or else "otherwise" is by c. 1300.

Related entries & more 
Advertisement
hit-or-miss (adv.)
"at random," c.1600, from hit (v.) + miss (v.).
Related entries & more 
tumour (n.)
chiefly British English spelling of tumor; see -or.
Related entries & more 
nor (conj.)

"and not," mid-13c., from ne (adv.) "no" + or (conj.), or else a contraction of Middle English nauther (see neither) and influenced in form by or. Generally correlative to neither or some other negative.

Related entries & more 
vapour (n.)
chiefly British English spelling of vapor; see -or.
Related entries & more 
Advertisement
savoury 
chiefly British English spelling of savory; also see -or.
Related entries & more 
behaviour (n.)
chiefly British English spelling of behavior; for suffix, see -or.
Related entries & more 
demeanour 
chiefly British English spelling of demeanor; for suffix, see -or.
Related entries & more 
neighbourhood 
chiefly British English spelling of neighborhood; for spelling, see -or.
Related entries & more 
labourer (n.)
chiefly British English spelling of laborer; for suffix, see -or.
Related entries & more