Tim Bowen gives us double the fun in his examination of this versatile word.
The word double can function as an adjective (e.g. a double murder, a double portion), a verb (e.g. ‘The population of the city has doubled over the past twenty years’), a determiner (e.g. ‘He now earns double the amount he used to’ or ‘It’ll cost you double what you paid last year’) and a noun.
In the latter category, double has several meanings. It is normally used with the indefinite article, as in ‘Did you know you have a double? She’s the spitting image of you’ and ‘Two brandies please and make mine a double’. Used with the definite article, it refers to victory in two different sporting competitions, as in ‘Bayern Munich won the double in Germany last season’.
In the plural, doubles specifically refers to a game of tennis played by four players, two on each side, as in ‘Nestor and Mladenovic won the mixed doubles at Wimbledon this year’.
Double can also be used as an adverb, as in ‘He was so drunk he said he was seeing double’ or ‘The pain in her stomach was so bad that she spent most of the morning bent double’.
It is also used in several phrasal verbs, notably double up, as in ‘In the corner was an old sofa that doubled up as Simon’s bed’ and double back, meaning to turn and go back in the direction you have come from, as in ‘After walking for more than an hour, they doubled back through the field to the village’.