No, it is not a preposition. The word tenants is a plural noun.
I have not yet met the new tenants.
Incolae
the apartment was abandoned by its tenants
A room or set of rooms forming a separate residence within a house or block of apartments.
The definition of something describes exactly what the word is and how the word can be used. You will also see synonyms for the word and if the word is a noun or adjective when viewing the definition.
what is the definition of word-processing package
The dictionary definition of a word
a definition of a compound word is jack-ass.
The word that goes with that definition is "door."
The definition of the word cited is quote as evidence for or justification of an argument or statement. Another definition for the word cited is mention as an example.
The word Lululemon Athletica has a definition. The word (words) have no definition, but instead are a name of a yoga athletic gear. The word Lulemon Athletica has no definition.