Disappearing Idioms

SHIRTTAIL RELATIVES  

ORIGINS:
The etymological record of shirttail relative is sparse. According to Merriam-Webster's online dictionary, the word shirttail first appeared in 1809, and was used, as it is today to describe the bottom part of a shirt that is tucked into trousers. But to get to the idiomatic use of "shirttail" in the expression shirttail relative, we turn to British master word-detective Michael Quinion who's website quotes the following from the Dictionary of American Regional English (DARE):

"A 1922 book about the Appalachians remarks 'it still is common in many districts of the mountain country for small boys to go about through the summer in a single abbreviated garment and that hey are called 'shirt-tail'boys.'

I’m only surmising, but perhaps the image conjured up by the term shirt-tail boys, of Americans living in so remote a locale as to be almost foreigners, made other Americans associate shirttail with distant relatives, and sure enough, again according to Mr. Quinion:

“DARE has examples from 1927 forwards, such as shirt-tail kin and shirt tail cousin, as well as [shirttail relative].”

Another idiomatic use of shirttail, cited by the online Free Dictionary, describes the adjectival use of the word as denoting something “of little value; inadequate or small.” Here I’m guessing that the above definition emerged from a common opinion that this part of a shirt’s structure was considered plain and inconsequential; after all, once a shirt is worn and tucked in, the wearer cannot even see his or her shirttail and may soon give little thought of it. Which, when you think of it, is a way of describing long-lost-from-memory relatives.