What is the meaning of the phrase Three in One?

Answer 1

It depends entirely on the context. Generally it would mean that one product or device has 3 functions.

Could it be a reference to the christian doctrine of the trinity as explained by st. Patrick using the shamrock??

...mostly a 3 in one is a long tray from a Chinese take away with chips, fried rice and curry sauce. used for making sure students don't die of starvation before paying back their loans :)

Answer 2

for shapes tri and uni

for Spanish uno trace

one three