c.1500, from Gaelic and Irish bogach "bog," from adjective bog "soft, moist," from PIE *bhugh-, from root *bheugh- "to bend" (see bow (v.)). Bog-trotter applied to the wild Irish from 1670s.
"to sink (something or someone) in a bog," c.1600, from bog (n.). Intransitive use from c.1800. Related: Bogged; bogging.
To become helpless and immobile, as if mired in a bog: On the one hand a threat had been neutralized, but we were bogging down again (1920s+)