All 96 Two-letter Words With Definitions
in the Official Scrabble Players Dictionary

AA - rough, cindery lava EX - the letter "X" OH - to exclaim in surprise
AB - abdominal muscle FA - a tone of the scale OM - a mantra
AD - advertisement GO - to move along ON - batsman's side of wicket
AE - one HA - sound of surprise OP - a style of abstract art
AG - pertaining to agriculture HE - male person OR - the heraldic color gold
AH - expresses delight HI - used as a greeting OS - a bone
AI - three-toed sloth HM - expresses consideration OW - expresses pain
AL - an East Indian tree HO - expresses surprise OX - a clumsy person
AM - form of "to be" ID - part of the psyche OY - expresses dismay
AN - indefinite article IF - a possibility PA - father
AR - the letter "R" IN - to harvest PE - a Hebrew letter
AS - to the same degree IS - form of "to be" PI - a Greek letter
AT - in the position of IT - neuter pronoun RE - a tone of the scale
AW - expresses protest JO - sweetheart SH - urges silence
AX - cutting tool KA - (Egyptian) spiritual self SI - ti (a tone of the scale)
AY - affirmative vote LA - tone of the scale SO - sol (a tone of the scale)
BA - (Egyptian) eternal soul LI - Chinese unit of distance TA - expression of gratitude
BE - to have actuality LO - expresses surprise TI - a tone of the scale
BI - a bisexual MA - mother TO - in the direction of
BO - a pal ME - personal pronoun UH - expresses hesitation
BY - a side issue MI - tone of the scale UM - indicates hesitation
DE - of; from - used in names MM - expresses assent UN - one
DO - a tone of the scale MO - a moment UP - to raise
ED - pertaining to education MU - a Greek letter US - personal pronoun
EF - the letter "F" MY - possessive pronoun UT - musical tone (is now DO)
EH - expresses doubt NA - no; not WE - pronoun
EL - elevated railroad NE - born with the name of WO - woe
EM - the letter "M" NO - a negative reply XI - a Greek letter
EN - the letter "N" NU - a Greek letter XU - monetary unit of Vietnam
ER - expresses hesitation OD - a hypothetical force YA - you
ES - the letter "S" OE - Faeroe Islands whirlwind YE - you
ET - a past tense of eat OF - coming from YO - used to call attention

New official words in OSPD4:
FE - a Hebrew letter
KI - the vital force in Chinese thought
OI - oy
QI - the vital force that in Chinese thought is inherent in all things
ZA - pizza