Apposite and opposite sound so much alike that you would expect them to have a common ancestor—and they do: the Latin verb pōnere, which means "to place, set.” The prefixes that we see in the pair, ap- and op-, specify the kind of placement. Apposite is from appōnere, meaning “to place near,” and opposite is from oppōnere, one meaning of which is "to place (over or against).” Opposite is of course the far more common word, but apposite is useful too and is, ahem, apposite in descriptions of what is very appropriate or suitable for something, as in “an apposite comment.”