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Medical terminology is composed of a prefix, root word, and suffix:
Prefix: A prefix is placed at the beginning of a word to modify or change its meaning. Pre means "before." Prefixes may also indicate a location, number, or time.
Root: central part of a word.
Suffix: The ending part of a word that modifies the meaning of the word.
Additional resources:   [Intro to med terms] [Med terms rules] [Med term reference] [Word building reference]  [Practice Exams]

Alphabetical Listing of Med Terms

a b c d e f g h i j k l m
n o p q r s t u v w x y z

Med terms ‘O’- roots in medical terminology

Medical terminology is used to precisely describe the human body components, processes, illnesses, medical procedures, and pharmacology. Medical terms are used in the field of medicine, and clinical settings. This section deals with med terms beginning with the letter "O", and features prefixes, suffixes and roots in medical terminology.

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This section was developed for 'speed learning' of medical terminology. Start by reviewing the meanings for a block of medical terms, and then go back and choose a previous term randomly and try to recall the meaning of that particular medical term before hovering over the term to determine the answer. These frequent mini-tests will accelerate the learning process and in a relatively short period of time, you will be able to quickly recall the meaning of all of the listed medical terms. This method of learning is superior to flash cards because of the frequent exposure and testing of your recall.


obstetr/o   pregnancy; birth
octa-, octi- eight
ocul/o   eye
odont/o   tooth
odyn/o   pain
-oid   resembling; derived from
-ole   little; small
ole/o   oil
olecran/o   olecranon (elbow)
olig/o   scanty
om/o   shoulder
-oma   tumor; mass; fluid collection
omphal/o   umbilicus (navel)
onc/o   tumor
-one   hormone
one   mono, uni
onych/o   nail (of fingers or toes)
o/o   egg
oophor/o   ovary
-opaque   obscure
ophry/o   eyebrow
ophthalm/o   eye
-opia   vision condition
opisth/o   backward, behind
-opsia   vision condition
-opsy   view of
opt/o   eye; vision
optic/o   eye; vision
-or   one who
or/o   mouth
orch/o   testis
orchi/o   testis
orchid/o   testis
-orexia   appetite
organ/o   organ
orth/o   straight
osche/o   scrotum
-ose   full of; pertaining to; sugar
-osis   condition, usually abnormal
-osmia   smell
osphresi/o   sense of smell
ossicul/o   ossicle (small bone)
oste/o   bone
-ostosis   condition of bone
ot/o   ear
-otia   ear condition
-ous   pertaining to
ov/o   egg
ovari/o   ovary
ovul/o   egg
ox/o   oxygen
-oxia   oxygen
oxy-   swift; sharpp; acid
oxysm/o   sudden

Additional Resources

Check out the following resources to support your learning and understanding of roots, suffixes and prefixes in medical terminology:

Med terms ‘O’- roots in medical terminology