The list below captures some of the most common abbreviations used on the forums. If you are aware of any that are not listed here, feel free to contact a mod and let us know.
Note: Not every former band member or every song has a commonly used abbreviation.
An alphabetical list is below in the next post.
Band Members:
JP - John Petrucci
JM/JMX - John Myung
JLB - James LaBrie
JR - Jordan Rudess
MM - Mike Mangini
Former Members:
MP - Mike Portnoy
KM - Kevin Moore
DS - Derek Sherinian
CD - Charlie Dominici
Studio Albums/EP:
WDADU - When Dream and Day Unite
I&W - Images and Words
ACOS - A Change of Seasons
FII - Falling Into Infinity
SFAM - Scenes From a Memory
SDOIT/6DOIT - Six Degrees of Inner Turbulence
TOT - Train of Thought
8VM - Octavarium
SC - Systematic Chaos
BC&SL or BCSL - Black Clouds and Silver Linings
ADTOE - A Dramatic Turn of Events
DT12 - Dream Theater (Self Titled)
Live Releases:
LATM - Live at the Marquee
OIALT - Once in a Livetime
5YIALT - 5 Years in a Livetime
LSFNY - Live Scenes From New York
L@B - Live at Budokan
CIM - Chaos in Motion
LALP - Live at Luna Park
Studio Songs:
When Dream and Day Unite
AFIL - A Fortune in Lies
SS - Status Seeker
YJ - Ytse Jam
TKH - The Killing Hand
LFAGA - Light Fuse and Get Away
TOWHTSTS - The Ones Who Help to Set the Sun
OAMOT - Only a Matter of Time
Images and Words
PMU - Pull me Under
TTT - Take the Time
UAGM - Under a Glass Moon
WFS - Wait for Sleep
LTL - Learning to Live
Awake
CIAW - Caught in a Web
IF - Innocence Faded
AMBI - the A Mind Beside Itself suite
LSOAD - Lifting Shadows off a Dream
SDV - Space-dye Vest (note: "SDV" can also refer to Strange Deja Vu)
Falling Into Infinity
NM - New Millennium
YNM - You Not Me
HY - Hollow Years
BMS - Burning My Soul
HK - Hell's Kitchen
LITS - Lines in the Sand
TAMP - Take Away My Pain
JLMB - Just Let Me Breathe
ToT - Trial of Tears (note: the "of" is typically lower case to distinguish between this song and the Train of Thought album, which is commonly abbreviated "TOT")
Scenes From a Memory
SDV - Strange Deja Vu
FT - Fatal Tragedy
BTL - Beyond This Life
TDOE - The Dance of Eternity
TSCO - The Spirit Carries On
FF - Finally Free
Six Degrees of Inner Turbulence
TGP - The Glass Prison
BF - Blind Faith
TGD - The Great Debate
6DOIT - Six Degrees of Inner Turbulence
II. ATC - About to Crash
III. WIMH - War Inside My Head
IV. TTTSTA - The Test That Stumped Them All
V. GK - Goodnight Kiss
VII. ATCR - About to Crash (Reprise)
VIII. LT/GF - Losing Time/Grand Finale
Train of Thought
TDS - This Dying Soul
ES - Endless Sacrifice
HTF - Honor Thy Father
SOC - Stream of Consciousness
ITNOG - In the Name of God
Octavarium
TROAE - The Root of All Evil
TALW - The Answer Lies Within
IWBY - I Walk Beside You
SS - Sacrificed Sons
8VM - Octavarium
Systematic Chaos
ITPOE - In the Presence of Enemies (note: sometimes, people use ITPOE1 and ITPOE to refer to part 1 or part 2)
CM - Constant Motion
TDEN - The Dark Eternal Night
POW - Prophets of War
TMOLS - The Ministry of Lost Souls
Black Clouds and Silver Linings
ANTR - A Nightmare to Remember
AROP - A Right of Passage
TSF - The Shattered Fortress
TBOT - The Best of Times
TCOT - The Count of Tuscany
A Dramatic Turn of Events
OTBOA - On the Backs of Angels
BMUBMD - Build Me Up, Break Me Down
LNF - Lost Not Forgotten
TITL - This is the Life
BITS - Bridges in the Sky
FFH - Far From Heaven
BAI - Breaking All Illusions
BTS - Beneath the Surface
Dream Theater
FAS - False Awakening Suite
TEI - The Enemy Inside
TLG - The Looking Glass
EM - Enigma Machine
TBP - The Bigger Picture
BTV - Behind the Veil
STR - Surrender to Reason
AFTR - Along for the Ride
IT - Illumination Theory