Medical Terminology – Common Prefixes (Location, Number, Description)

Spatial (Positional) Prefixes

• Before

  • pre-, pro-, ante-
    • Denote temporal precedence or location in front of something.
    • Example: prenatal (before birth), prologue (section before the main text), antepartum (before labor).

• Behind / Backward

  • retro-, dors/o-, poster/o-
    • Indicate a position to the rear or movement backward.
    • Example: retrograde (moving backward), dorsal (pertaining to the back), posterior (toward the back of the body).

• Below / Under

  • infra-, sub-, hypo-
    • Refer to something situated beneath or deficient in amount.
    • Example: infrascapular (below the scapula), subcutaneous (under the skin), hypoglycemia (low blood sugar).

• Between / Among

  • inter-
    • Positioned or occurring between two structures.
    • Example: intercostal (between the ribs).

• Inside / Within

  • endo- (inside)
    • Example: endoscope (instrument to view the inside).
  • intra- (within)
    • Example: intravenous (within a vein).

• Middle

  • mid-
    • Example: midbrain (the middle portion of the brain).

• Near / Beside / Abnormal

  • para-
    • Denotes adjacency, beside, or abnormal condition.
    • Example: paramedic (works beside physicians), parathyroid (beside the thyroid), paraplegia (abnormal paralysis).

• Outside / Outer / External

  • exo-, ecto-, extra-
    • Indicate outward position or origin.
    • Example: exoskeleton (outer skeleton), ectoderm (outer embryonic layer), extracellular (outside the cell).

• Side

  • later/o-
    • Example: bilateral (two sides), lateroflexion (bending to the side).

• Through / Across

  • dia-, per-
    • Passage through, complete, or across.
    • Example: dialysis (separation through a membrane), percutaneous (through the skin).

Numerical / Quantity Prefixes

• Fractions

  • deci-: one-tenth (\frac{1}{10})
  • centi-: one-hundredth (\frac{1}{100})
  • milli-: one-thousandth (\frac{1}{1000})

• Multiples

  • kilo-: one-thousand ( 1000 )

• Ordinals / Sequence

  • primi-, proto-: first
    • Example: primigravida (first pregnancy), prototype (first model).

• Cardinals

  • uni-, mono-: one
    • Example: unilateral (one side), monocyte (single cell).
  • diplo-, bi-: two
    • Example: diplopia (double vision), biceps (two heads).
  • tri-: three
    • Example: tricuspid (three cusps).
  • quadr-: four
    • Example: quadriplegia (paralysis of all four limbs).

• Half / Partial Absence

  • semi-, hemi-: half
    • Example: semilunar valve (half-moon shaped), hemiparesis (weakness of one side of the body).

• Zero / Absence

  • nulli-: none
    • Example: nullipara (a woman who has borne no children).

Descriptive / Qualitative Prefixes

• After / Following

  • post-
    • Example: postoperative (after surgery).

• Bad / Poor / Abnormal

  • mal-
    • Example: malnutrition (poor nutrition).

• Beyond / Change / Transformation

  • meta-
    • Example: metastasis (beyond original position; spread of disease).

• Both / Around

  • ambi-, amphi-
    • Convey duality or surrounding.
    • Example: ambidextrous (able to use both hands), amphibious (lives both on land and water).

• Different / Other

  • hetero-
    • Example: heterogeneous (different kind).

• Difficult / Painful / Faulty

  • dys-
    • Example: dysfunction (impaired function), dyspnea (difficult breathing).

• Double / Two-Fold (duplicate of “both” usage)

  • ambi-, amphi- (see above)

• Easy / Normal / Good

  • eu-
    • Example: euphoria (state of good feeling), euthyroid (normal thyroid function).

• Equal / Same

  • iso-
    • Example: isotonic (equal tension/pressure).

• False / Deceptive

  • pseudo-
    • Example: pseudocyesis (false pregnancy).

• Fast / Rapid

  • tachy-
    • Example: tachycardia (rapid heart rate).

Practical Tips & Significance

• Prefixes modify the meaning of root words; understanding them helps decode unfamiliar medical terms quickly.
• Many prefixes have overlapping meanings (e.g., endo- vs intra-). Context and combinational rules determine preference.
• Be aware of spelling changes when a prefix meets a root (e.g., sub + cutaneous ➜ subcutaneous).
• Ethically, precise terminology avoids miscommunication that could compromise patient safety (e.g., distinguishing hypoglycemia vs hyperglycemia).