Negation with non

To say that something is not the case, Latin uses the little word non. It is the everyday "not", and it is refreshingly simple: it does not change its form, and it normally sits directly in front of the word it denies - usually the verb.

Positive	Negative
Ambulo. - I am walking.	Non ambulo. - I am not walking.
Marcus dormit. - Marcus is sleeping.	Marcus non dormit. - Marcus is not sleeping.
Romani sunt. - They are Romans.	Romani non sunt. - They are not Romans.

Placed before another word, non denies just that word: non hodie - not today; non magnus - not big.

For English speakers: the great convenience is that Latin needs no helper verb. English has to insert "do" to say "I do not walk", but Latin just puts non before the verb: non ambulo. So do not look for a Latin word for "do" - there is none. Two small notes: to answer "no" as a full reply, Romans more often repeat the verb in the negative (Venisne? Non venio. - Are you coming? I am not) rather than using a bare "no", and for negative commands ("Do not...") Latin uses noli plus the infinitive (noli plorare - do not cry), not non.