If you believe the internet is the fount of all wisdom, giving free rein to bloggers to exercise their vocal cords, think again. Ancient English cliches and expressions are being mangled by the culture of cut and paste and the spread of unchecked writing on the internet.

According to the Oxford English Corpus, a database of a billion words, dozens of traditional phrases are now more commonly misspelled than rendered correctly in written English.

"Straight-laced" is used 66% of the time even though it should be written "strait-laced", according to lexicographers working for Oxford Dictionaries, who record the way English is spoken and written by monitoring books, television, radio and newspapers and, increasingly, websites and blogs.

"Just desserts" is used 58% of the time instead of the correct spelling, "just deserts" (desert is a variation of deserve), while 59% of all written examples of the phrase in the Corpus call it a "font of knowledge or wisdom" when it should be "fount".

It has become so widely used that the wrong version is now included in Oxford dictionaries alongside the right one.

Other mistakes fast becoming the received spelling include substituting "free reign" for the correct phrase, "free rein".

The original refers to letting a horse loose, but many use "reign" and assume the expression means to allow a free rule.

Other examples of common mistakes include "slight of hand" instead of "sleight", "phased by" when it should be "fazed by", "butt naked" instead of the correct "buck naked" and "vocal chords" for "vocal cords."

"We have to accept spelling is not fixed and can change over the years," said Catherine Soanes, of Oxford Dictionaries. "You only have to look back 100 years, when the word rhyme was spelled rime. But since then we adopted rhyme as the correct spelling because this is more like the Greek word from which it originally came."

She added: "Our Corpus has around 150m words from the web and the way words are written often has to do with familiarity.

"For instance, 35% of people say 'a shoe-in' when actually it should be 'a shoo-in'.

"But the original is an American phrase using a US version of the word "shoe" in the first place."

According to the Corpus, another linguistic trend is the American habit of turning two words into one, such as someday, anymore and underway.

The Corpus also records how some words are used almost exclusively to apply to men and others to women.

Only men seem to hijack, crouch, kidnap, rob, grin, shoot, dig, stagger, leap, invent or brandish.

Women, meanwhile, tend to be the only ones to consent, faint, sob, cohabit, undress, clutch, scorn or gossip.