Bog
Middle English: from Irish or Scottish Gaelic bogach, from bog ‘soft’.
wiktionary
From Middle English bog, from Irish and Scottish Gaelic bogach(“soft, boggy ground”), from Old Irish bog(“soft”), [1] from Proto-Celtic *buggos(“soft, tender”) + Old Irish -ach, from Proto-Celtic *-ākos.
The frequent use to form compounds regarding the animals and plants in such areas mimics Irish compositions such as bog-luachair(“ bulrush, bogrush”). [1]
Its use for toilets is now often derived from the resemblance of latrines and outhouse cesspools to bogholes, [2] [3] but the noun sense appears to be a clipped form of boghouse(“ outhouse, privy”), [4] which derived (possibly via boggard) from the verb to bog, [5] still used in Australian English. [3] The derivation and its connection to other senses of "bog" remains uncertain, however, owing to an extreme lack of early citations due to its perceived vulgarity. [6] [7]
See bug [8]
Of uncertain etymology, [9] although possibly related to bug in its original senses of " big" and "puffed up".
From bug off, a clipping of bugger off, likely under the influence of bog (coarse British slang for " toilet[s]").
etymonline
bog (n.)
"wet, soft, spongy ground with soil chiefly composed of decaying vegetable matter," c. 1500, from Gaelic and Irish bogach "bog," from adjective bog "soft, moist," from Proto-Celtic *buggo- "flexible," from PIE root *bheug- "to bend." Bog-trotter applied to the wild Irish from 1670s.
A bog is characterized by vegetation, decayed and decaying, and a treacherous softness. A quagmire or quag is the worst kind of bog or slough; it has depths of mud, and perhaps a shaking surface. A slough is a place of deep mud and perhaps water, but generally no vegetation. [Century Dictionary]
bog (v.)
"to sink (something or someone) in a bog," c. 1600, from bog (n.). Intransitive use "to sink or stick in a bog" is from c. 1800; with down (adv.) by 1848, American English. Related: Bogged; bogging.
