English can be a right dastard sometimes. Why not?

Question

Bastard, meaning one begotten and born out of wedlock, is a very old word from Old French (earliest OED citation 1297).

Dastard, meaning one who meanly or basely shrinks from danger; a mean, base, or despicable coward; one who does malicious acts in a cowardly, skulking way, so as not to expose himself to risk, appears to be of English formation and dates from the 15th century onwards (OED).

In the course of the 19th century a useful and idiomatic word, dastard, stopped being used at all (even though its adjectival form, dastardly, lives on (e.g. Whacky Races). During the 1800s all the sense of dastard, including especially it's use as a term of abuse, was subsumed under a similar-sounding word (bastard), whose abusive power until that point had been limited to implying a person was a mongrel, and an (animal of) inferior breed (OED).

This Ngram suggests that the decisive rise of bastard and decline of dastard occurred in the years following the First World War... Is there any specific reason why bastard became so popular and why dastard fell so completely out of use?

Answer 1

It's very hard to say why any word became less popular unless there's a very particular reason why it might (e.g. it is replaced by another word and we can explain its rise, or refers to something that itself is less common than it once was).

There is though a general trend of mildly insulting words becoming less popular. Cad, fink, blackguard, varlet are all examples of mild insults that seem to have fallen in use. Several others are hard to trace because they either already have other meanings (goat and several other animal-based insults, with the possible exception of bitch) or have acquired other meanings or context-specific uses (rogue, villain).

Likely at least part of the answer lies in the greater acceptability of terms generally considered stronger in more context. One might today not bother to say dastard where one can say fucking bastard. Even more so, one might today not bother to write or broadcast dastard were once using fucking bastard would not have gotten past censors.

Answer 2

Perhaps a clue could lie in the loss of taboos in language. The early 20th century is still that of censorship in newspapers, cinema and TV. Anything resembling foul language could easily be stricken off a copy.

"Bastard" was lying on the brink between the acceptable and the unacceptable, like many other words. The device of slightly altering the word to avoid foul language or blasphemy -- something called a euphemism and more colloquially (and specifically) minced oath -- is quite old and has been one of the ways to get around those limitations (another has been to use metaphoric expressions or code words).

By Golly => By God

Bull => Bullshit

Clearly the two words bastard and dastard are unrelated etymologically, but it's worth formulating the hypothesis that there has been a more or less conscious attraction of the first on the second, which has kept the obsolete dastard afloat longer than it should have in the normal course of things.

Today, the border markers have been shifted way beyond, so there does not seem any use for "dastard" and "dastardly". The liberation of language has provided the speakers of English with plenty of powerful terms to describe a disagreeable person (including the recently famous "son of a bitch").

Two border markers of today are the F. and the S. words.

• Please close the friggin' door.

• Oh, shoot. The bus is late again.

Or the use of (beep) in sound recordings.