Although one source source the answer as "...The term para- in English, is an affix of ancient Greek and Latin origin, mostly used as a prefix. Its most common meaning is "similar to" or "near to."
In Greek, παρά (para) means "beside," "with," or "alongside," such as in paragraph. In Latin, para means "against," "counter," "outside," or beyond. For example, parapluie in French means "counter-rain"�an umbrella..." it's not sufficient, in my opinion, to explain the many different applications of this appellation, so to speak. There are probably not many words in English that use a prefix more commonly used than
para. Parallel comes to mind as a word that uses para but defies the explanations provided as to why.
This provides a thorough essay on the subject...