NSA = No strings attached
AA = African American
OHAC mean in Relationship
No strings attached--the writer of the ad is looking for a casual sexual relationship without any interest in a dating relationship or commitment.
'NSA' means "no strings attached" - in other words, a one-time date, rather than an ongoing relationship.
In the personal ads that I have seen, LOS means Lost or Stolen.
I believe that you mean abbreviations and acronyms such as F (female), M (male), BBW (big beautiful woman), Bi (bisexual), LDR (long distance relationship), etc. See the link below for a guide.
Androgynous
For sex :)
Craigslist uses mw4mw, for man and woman on man and woman, but other sites may use different abbreviations.
Long Term RelationshipLTR in personal ads means long term relationship.
professional
water sports
Bareback, or no condom