a- (an before a vowel or h)
Not, Without, Lacking, Deficient
anti- (Ant- often before a vowel)
Against, Opposed To, Preventing, Relieving
di- (Rarely dis-)
Two, Twice, Double
ec- (ex before a vowel)
Out of, Away from
en- (em- before b, m, and p)
In, Into, Within
epi- (ep- before a vowel or h)
Upon, Over, Above
exo-
Outside, From the Outside, Toward the Outside
hypo- (hyp- before a vowel or h)
Under, Deficient, Below, Normal
peri-
Around, Surronding
dys-
Difficult, Painful, Defective, Abnormal
ecto- (ect- often before a vowel)
Outside of
endo-, ento- (end-, ent- before a vowel)
Within
hemi-
Half, Partial; Often one side of the body
hyper-
Over, Above, Excessive, Beyond Normal
mono- (mon- before a vowel or h)
One, Single
syn- (sym- before b, p, and m)
Together, With, Joined