Par

The Latin word “pār” means “even or equal”. This is not really surprising if you know a lot of words containing “par” that are somehow related to the equality or comparison between two things (I already used one of them now, comparison). For example, “pair”, parity”, “disparity”, “disparage”, and so on.

These words totally make sense. Parity can simply mean “equality of rank or status”, or in mathematics, it refers to a set with certain properties of two disjoint subsets. With the prefix “dis-“, disparity obviously means “the state of being of unequal rank”. Disparage means “to treat as something lower than it is”.

The word “peer” was not really connected to “equal” at first to me, because I just regarded this word as something like “pal” or “friend”. But this word is defined as “a person who is the same age or has the same social position or the same abilities” in the Cambridge Dictionary and it makes perfect sense.

Finally, there is one hypothesis that “apparel”¹ ultimately comes from the Latin pār. In the OED, there are many archaic meanings such as “to make ready” or “to dress up”, which kind of have the sense of “to make equal or fit”.