A tuple containing ‘n’ components is known as a n-tuple. For example, 4-tuple (or ‘quadruple’).

We are all familiar with these terms:

Single
Pair
Triple
Quadruple
Quintuple
Sextuple
Septuple
and so on..

We pronounce the ‘uple words with an ‘oo’ sound, like quadruple

kwo-droo-puhl

And not

kwo-druhp-uhl

Likewise, the pronunciation for ‘quintuple’ is

kwin-too-puhl

The only time the sound changes is when the suffix changes, like in quintuplet (to make it a noun), which is pronounced

kwin-tuhp-lit

In order for the ‘u’ in tuple to be pronounced as a ‘uh’ sound (like in supple) it should have a double-p. Just like ripple, tipple and of course, nipple.

But it doesn’t. It only has one.

Likewise, if the word as an ‘e’ on the end then the vowel is pronounced in full.

cap -> cape
met -> mete
sit -> site
dot -> dote
cub -> cube

So “tup” (pronounced “tuhp”), should be pronounced “tyoop” when you add an “e”.

Of course there are always exceptions to the rule in English (that’s what helps make English great!), but there is a similar Latin-based word that might shed some light, duple (from the Latin “duplus” meaning twofold or double). This word is only pronounced one way and that is with the full ‘u’ sound (doo-puhl).

If that’s not enough to convince you, here are some examples where the middle vowel (like in duple and tuple) is pronounced as a long sounding vowel

cable
fable
gable
ladle
maple
noble
ruble
sable
table

So don’t be a dupe, learn to say tupe!