multiply
Crowded hospital wards multiply multiply resistant bacteria.
The first 'multiply' is the familiar verb, pronounced /ˈmʌltɪplaɪ/ (ending like 'fly'): crowded wards cause the bacteria to increase greatly in number. The second is the much rarer adverb, pronounced /ˈmʌltɪpli/ (ending like 'simply'), meaning 'in several ways at once', so 'multiply resistant' bacteria shrug off more than one antibiotic. The doubled word forces the reader to reparse mid-sentence, and the spoken version only makes sense once the voice shifts from '-ply' to '-plee', a heteronym whose two halves are split not by stress but by a single final vowel.
Meanings
To increase, or cause to increase, greatly in number or quantity; in arithmetic, to find the product of two numbers.
- Rabbits multiply quickly when food is plentiful.
- Multiply seven by eight to get fifty-six.
In several or many ways, places, or instances at once; used chiefly before adjectives and participles in technical writing.
- The lab isolated a multiply resistant strain of staphylococcus.
- In topology, an annulus is a multiply connected region.
Word origin
The verb comes from Old French 'multiplier', from Latin 'multiplicare' (to make many), built on 'multiplex', from 'multus' (much, many) plus '-plex' (-fold). The adverb is a much later English formation, simply the adjective 'multiple' plus the adverb suffix '-ly', with the 'e' of 'multiple' swallowed exactly as in 'simple' to 'simply'. The two converged on one spelling by coincidence of that contraction.
Fun fact
'Multiply' has an exact spelling twin in 'supply': the familiar verb /səˈplaɪ/ and the rare adverb /ˈsʌpli/, meaning 'in a supple manner' (supple plus -ly). In both pairs the adverb is born from an adjective ending in '-ple', which is why its last syllable sounds like 'simply' rather than 'apply'. Mathematicians use the adverb constantly: a 'multiply connected' region is one with holes in it, like a doughnut.