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always: always: [13] In Old English, the expression was alne weg, literally ‘all the way’. It seems likely that this was used originally in the physical sense of ‘covering the complete distance’, but by the time it starts to appear in texts (King Alfred’s is the first recorded use, in his translation of Boethius’s De consolatione philosophiae around 888) it already meant ‘perpetually’. Alway survived into modern English, albeit as an archaism, but began to be replaced as the main form by always in the 12th century.

The final -s is genitive, not plural, and was originally added to all as well as way: alles weis. It has a generalizing force, much as in modern English one might say of a morning for ‘every morning’.
=> way
always (adv.): mid-14c., compound of Old English phrase ealne weg "always, quite, perpetually," literally "all the way," with accusative of space or distance, though the oldest recorded usages refer to time; see all + way (n.). The adverbial genitive -s appeared early 13c. and is now the standard, though the variant alway survived into 1800s. OED speculates allway was originally of space or distance, "but already in the oldest Eng. transferred to an extent of time."
anyways (adv.): see anyway.
edgeways (adv.): also edge-ways, "with the edge turned forward or toward a particular point," 1560s, from edge (n.) + way (n.). First attested form of the word is edgewaie; the adverbial genitive -s appears by 1640s. Edgewise (1715) appears to be a variant, based on otherwise, etc. See edge (v.).
As if it were possible for any of us to slide in a word edgewise! [Mary Mitford, "Our Village," 1824].
To edge in a word in this sense is from 1680s.
folkways (n.): coined 1906 in a book of the same name by U.S. sociologist William Graham Sumner (1840-1910); see folk (n.) + way (n.).
Folkways are habits of the individual and customs of the society which arise from efforts to satisfy needs. ... Then they become regulative for succeeding generations and take on the character of a social force. [Sumner, "Folkways"]
Sumner also often is credited with ethnocentrism, which is found in the same book but is older.
leastways: 1825, colloquial, from least + way (n.). Regarded as vulgar, but simply a one-word form of Chaucer's leest weye (late 14c.).
lengthways: 1590s, from length + way (n.), with adverbial genitive -s.
longways (adv.): 1580s, from long (adj.) + way (n.) + adverbial genitive -s.
needways (adv.): "by necessity," c. 1300, a northern and Scottish word, marked as obsolete in OED; from need (n.) + way (n.), with adverbial genitive.
sideways (adv.): 1570s, from side (n.) + way (n.), with adverbial genitive. To look sideways "cast scornful glances" is recorded from 1844.
slantways (adv.): 1826, from slant (n.) + way (n.) + adverbial genitive -s.
wayside (n.): "the side of the road," c. 1400, from way (n.) + side (n.). To fall by the wayside is from Luke viii:5.