When, for example, somebody wishes me a Merry Christmas, can I say likewise as a reply? Is it common?
It's not really appropriate here, if all they say is, "Merry Christmas.
It's used when you want to say you feel the same way as the first speaker...............
"I'm very pleased to meet you."
"Likewise, I'm sure"
"I'm really keen to see that new film."
"Likewise."
"I don't really care for garlic in my food."
"Likewise, it's too strong a taste for me."
If you're wished a Merry Christmas, you'd usually respond with, "Same to you" or "And a Merry Christmas to you, too."
If they say
specifically, "
I wish you a Merry Christmas" then you
could respond with, "Likewise."
buggles (not a teacher)