i Register
In some senses, nnr is marked as UK, rare. Watch for register when choosing this word.
noun
Initialism of national nature reserve.
phrase
Abbreviation of no need to respond or need not respond.
Initialism of no, not really.
Initialism of not nappy related (used in forums dedicated to nappies (diapers) to signify that the succeeding post is not related to nappies; i.e. it is off-topic).
phrase
Alternative letter-case form of NNR.