One of the differences between American and British English is the usage of the words round and around. Americans use around in contexts in which most British speakers prefer round.
The word round has five grammatical functions: noun, verb, adjective, adverb, and preposition.
The fighter was able to go another round. (noun)
We watched as the runner rounded first base. (verb)
Do you want a round plate or a square one? (adjective)
The bridge was out, so we had to go round. (adverb)
The tiger ran round the tree. (preposition)
Round came into the language as a noun meaning “a circular object.” At various times, the “circular object” was a racecourse, a ring, and a coin. In a text from 1325, round is the word used for a diadem encircling the head of a man in a painting. Chaucer used round in the sense of a globe. In Macbeth, Shakespeare used round as a word for a sovereign’s crown.
Around was formed from the noun round by adding the prefix a-, a variation of the prefix on-, creating an adverb that meant “in a circle.”
In some contexts, British speakers use round and around interchangeably; for example, either “He put his arm round her,” or “He put his arm around her.”
Otherwise, according to a note in the British English section of Oxford Dictionaries, there’s a general preference among British speakers to use round for “definite, specific movement,” and around in contexts that are less definite. For example,
She turned round.
A bus came round the corner.
She wandered around for ages.
The computer cost around £3,000.
According to a rumor circulating around the track, he’s using steroids.
American usage sometimes reflects British usage by using round, but around is more common.
Although the Oxford note says that in most contexts, “round is generally regarded as informal or non-standard,” I haven’t found anything in Merriam-Webster or the Chicago Manual of Style to indicate that using round the way the British do is “non-standard” in American usage. It may be old-fashioned, but it is not unknown in American writing:
By the rude bridge that arched the flood,
Their flag to April’s breeze unfurled,
Here once the embattled farmers stood
And fired the shot heard round the world. –Ralph Waldo Emerson, “Concord Hymn,” 1837
I should like if my sisters are well and all the people round the neighborhood. –letter from Peter Van Wagener (son of Sojourner Truth), March 22, 1841
The usage is still seen in emails and web comments by American speakers:
We live downtown and I take them round the neighborhood, –A mother talking about taking children trick or treating in Sacramento, California.
One of the latest scams going round is that someone will stop you and ask if you are interested in perfume, –email debunked on Snopes.com/.
The strange form ‘round crops up in both British and American contexts, but as round is not a shortening of around, and as there’s no law against the American use of round to mean around, the apostrophe makes no sense in either dialect.