Of a Preposition
A Preposition is a part of speech commonly set before another word. Words, however, do not eat each other, though men have been known to eat words. Ab, ad, ante, &c. prepositions.
Sometimes a preposition is joined in composition with another word, as prostratus, knocked down—floored.
Tullius ab aquario prostratus est:
Tully was knocked down by a waterman.