thank you (and its responses). 
“Thank you” remains the best, most serviceable phrase, despite various attempts to embellish it or truncate it: “thanking you in advance” (presumptuous and possibly insulting), “thank you very much” (with a trailer of surplusage), “thanks” (useful on informal occasions), “many thanks” (informal but emphatic), *”much thanks” (archaic and increasingly unidiomatic), *”thanks much” (confusing the noun with the verb), and *”thanx” (unacceptably cutesy).
“Thank-you,” n., is hyphenated thus {a thousand thank-yous}.
The traditional response to “Thank you” is “You’re welcome.” Somehow, though, in the 1980s, “You’re welcome” came to feel a little stiff and formal, perhaps even condescending (as if the speaker were saying, “Yes, I really did do you a favor, didn’t I?”). As a result, two other responses started displacing “You’re welcome”: (1) “No problem” (as if the speaker were saying, “Don’t worry, you didn’t inconvenience me too much”); and (2) “No, thank you” (as if the person doing the favor really considered the other person to have done the favor). The currency of “You’re welcome” seems to diminish little by little, but steadily. Old-fashioned speakers continue to use it, but its future doesn’t look bright.
*Invariably inferior form.
For information about the Language-Change Index click here.
——————–
Quotation of the Day: “Most slang words are heard for a few years and then disappear, usually forever. Some are fated to endure solely as slang without ever being admitted to polite usage . . . . But occasionally some slang words — like ‘joke,’ ‘fad,’ ‘boom,’ ‘crank,’ and ‘slump’ — become respectable items in the vocabulary.” Peter Farb, Word Play 86 (1974; repr. 1975).