Implore, explore, deplore; these three words clearly share a root but have very different meanings. What can this -plor- root mean?
Dictionary.com gives several related meanings for the Latin word plōrāre: "to lament; to cry out; to wail". Thus to deplore something is to lament its existence. To implore that someone do something is to request it piteously, all full of tears.
Where does explore fit in? Dictionary.com suggests that in this case -plor- means "to cry out, prob. orig. with reference to hunting cries". Thus it seems that explore harks back to adventurous hunting expeditions. Perhaps in ancient times that was one of the main reasons to venture beyond familiar lands.