domus

Domus, domus is fourth declension feminine, but it borrows second declension endings so freely that the ablative singular is domo and the accusative plural is usually domos. Its real peculiarity is that it keeps a locative, one of a tiny handful of nouns that do: domi means at home, domum means homewards, domo means from home, and none of the three takes a preposition. That is the single most useful thing to know about the word, because in domum or ad domum reads wrong to a Roman ear.