Word of the Day
1 A person who shares a bed with another.
1.1 A person or thing allied or closely connected with another.
According to etymolonline.com “fellow” is historically a genderless term, so bedfellow easily and effectively expresses close associations of all kinds. Though the common phrase “strange bedfellows”, to describe unexpected affiliations, may be the most familiar usage.
There is also the archaic term, “wedfellow”, referring to a spouse. Perhaps, with same-sex marriages having become common, that term will be resurrected.