Scrabble/Two-Letter Words

Having a knowledge of all of the two-letter words will greatly improve your Scrabble gameplay, either when you need to build off an existing tile to form a new word, or at the end of the game when you have two or three tiles left and need to dump them off as quickly as possible. Two-letter words are also very useful when playing a new word parallel (alongside, above, or beneath) to an existing word.

Tournament Word List (TWL) 2-letter words

There are 107 acceptable 2-letter words listed in the Official Scrabble Players Dictionary, 6th Edition (OSPD6), and the Official Tournament and Club Word List (OTCWL, or simply, TWL):

AA, AB, AD, AE, AG, AH, AI, AL, AM, AN, AR, AS, AT, AW, AX, AY, AO

BA, BE, BI, BO, BY
DA, DE, DO
ED, EF, EH, EL, EM, EN, ER, ES, ET, EW, EX
FA, FE
GI, GO
HA, HE, HI, HM, HO
ID, IF, IN, IS, IT
JO
KA, KI
LA, LI, LO
MA, ME, MI, MM, MO, MU, MY
NA, NE, NO, NU
OD, OE, OF, OH, OI, OK, OM, ON, OP, OR, OS, OW, OX, OY
PA, PE, PI, PO
QI
RE
SH, SI, SO
TA, TE, TI, TO
UH, UM, UN, UP, US, UT
WE, WO
XI, XU
YA, YE, YO
ZA

Collins Scrabble Word (CSW) 2-letter words

There are 20 2-letter words that are acceptable in only CSW, making a total of 127 CSW-acceptable 2-letter words:

CH
DI
EA, EE
FY
GU
IO
JA
KO, KY
NY
OB, OO, OU
ST
UG, UR
YU
ZE, ZO

Note: PH was removed from CSW in 2007.