#ab

What does "ab" mean?
amateurs_bnw, amateurs_Bnw, ae_bnw, all_bnwshots, animal_brilliance, AsianBeauty, awesome_bw, Amateurs_Bnw, absolute_bnw, awesome_bnw, amar_bw, andaluciaviva_bw, AlternativeBrewing, ali_bader, AnimeBoy, alza_boutique, AudiBelgium, AudiBlack, audi_black, Audi_black, AlpinaB6, AlpinaB7, AngryBird, amirrez_bz, AngryBirds, AllBlacks, aby_bnw, art_blend, akas_bashi, aks_baran

ab-s 1339976 ab-c 62041 ab-h 55987 ab-g 48773 ab-i 38285 ab-a 12829 ab-udhab-i 436618 ab-aya 101947 ab-ril 162313 ab-stract 580367 ab-la 19268 ab-iye 77554 ab-andoned 173031 ab-kc 16973 ab-dl 18321 ab-ba 17227 ab-outlastnight 215300 ab-out 56732 ab-straction 50800 ab-by 16110 ab-mlifeiscolorful 115951 ab-ac 14336 ab-andonedplaces 65168 ab-mlifeissweet 36917 ab-mhappylife 47905 ab-c7eyewitness 33639 ab-urrida 109772 ab-nehmen 101414 ab-nehmen2016 45392 ab-dos 31397 ab-ençoada 28201 ab-stractart 261150 ab-leton 56441 ab-end 32812 ab-aikan 46126 ab-uja 33079 ab-use 17229 ab-lam 18496 ab-ruzzo 45336 ab-outalook 71675 ab-undance 65781 ab-road 21405 ab-saremadeinthekitchen 86314 ab-urrido 57513 ab-stractpainting 43538 ab-arth 17824 ab-bey 11811 ab-nehmenohnezuhungern 13625 ab-solut 22404 ab-endessen 38001 ab-stractphotography 20640 ab-pbh29 15998 ab-ercrombie 23569 ab-stractartist 27383