Little useful lexicon...

... look at Google if a term is missing =)

AF : Auto Focus
CA : Chromatic Aberration
DOF : Depth Of Field (= PDC)
DSLR : Digital Single Lens Reflex
FA : Full Aperture (= PO)
FOV : Field Of View
FSU : Former Soviet Union
LTM : Leica Thread Mount
MF : Moyen Format (4.5×6, 6×6, 6×7...)
MF : Manual Focus
OOF : Out Of Field
P&S : Point & Shoot
PDC : Profondeur De Champ (= DOF)
PO : Pleine Ouverture (= FA)
RF : RangeFinder
SLR : Single Lens Reflex
TLR : Twin Lens Reflex

AME : Apo-Macro-Elmarit (stands for Apo-Macro-Elmarit-R 100mm ƒ/2.8)
DMR : Digital-Modul-R
HCB : Henri Cartier-Bresson ; master of street photography and highly praised guru of rangefinder users

In case you read french-speaking forums :
ACH : Achète ("WTB / Want To Buy" in english-speaking forums)
HS : Hors-sujet ("OT / Off Topic" in english-speaking forums)
VDS : Vends ("FS / For Sale" in english-speaking forums)