We tend to think that we are given to irrational hatreds of Americanisms, but Americans have mirror-image distastes for British usages. 'At best, orientate is a back-formation used humorously to make the speaker sound pompous. The correct word is the verb orient,' says a helpful language website made in America. It is quite wrong.
'In the perverse way in which such things often happen,' wrote good old Robert Burchfield in his edition of Fowler, 'these two verbs drawn from the same base (French orienter, 'to place facing the east') have fallen into competition with one another in the second half of the 20th century'. It still continues.
Orient came into English in the middle of the 18th century; orientate 100 years later. But there is no need to invoke 'back-formation'. Orientate corresponds to orienter as or felicitate does to feliciter.
It is disturbing to contemplate how these words creep into the language. It could be little more than a historical coincidence that today, we don't see people going around, feliciting one another. I would felicit you, and you would felicit me, and parents would be forever bursting in on their son feliciting their neighbours daughter, Felicity, in an illicit manner. This illicit feliciting would certainly not felicitate family felicity. Some kids wouldn't even worry about the feliciting, and just skip that bit, and get straight to the illiciting, though more than one of them would get a shock when they discover that their partner was dupliciting them.
On the whole, I'm rather glad that this furtive and sometimes downright felonious feliciting has not crept into the English language. We may just have avoided the breakdown of society.
"You take this cart of puppies, Tom, while I felicit Jane."
Aaaaargh! The kids are feliciting one another again!
(Cross-posted on Vibewire.)