This list covers most (but not all) of the abbreviations you might see while looking for a place to live. Feel free to refer to this guide if you are not sure what something means.
AB Altbau an old building
Bj. Baujahr year of construction
DG Dachgeschoss top floor
EBK Einbauküche built-in kitchen
EG Erdgeschoss ground floor
KM Kaltmiete not including utilities
KT Kaution deposit
NB Neubau new building
NK Nebenkosten utility costs
NR Nichtraucher non-smoker
OG Obergeschoss upper floor
inkl. Inklusive inclusive
v-möb Vollmöbliert fully furnished
WC Toilette toilet
WBS Wohnberechtigungsschein (see below)
WG Wohngemeinschaft apartment sharing
WM Warmmiete including heating and water
A Wohnberechtigungsschein (WBS) is given to people with low income and some apartment listings will say WBS only – this is because there is usually some additional funding paid towards housing for people with WBS status and the apartment is offered for that specifically. For more information on WBS and whether you can apply, please see (in German only): https://service.berlin.de/dienstleistung/120671/ or check the estimator here: https://ssl.stadtentwicklung.berlin.de/wohnen/wbs/wbsformular.shtml