- Cladinose
- Cladistics
- Cladogram
- Cladosporium
- Cladribine
- Clanging
- Clara cells
- Clarithromycin
- Clark level
- Clark's level
- Clarke's nucleus
- Claspers
- Class III β-tubulin
- Class switch recombination
- Classic autism
- Classic galactosemia
- Classical Hodgkin lymphoma
- Classical complement pathway
- Classical conditioning
- Classical genetics
- Classical pathway
- Classical pharmacology
- Classical swine fever virus
- Classical test theory
- Classification
- Classification of obesity
- Clastogen
- Clastogenic
- Clathrate
- Clathrin
- Clathrin coated vesicles
- Clathrin-coated vesicles
- Claude's syndrome
- Claudication
- Claudin
- Claustrophobia
- Claustrum
- Claviceps
- Claviceps purpurea
- Clavicle
- Clavicle fracture
- Clavipectoral fascia
- Clavulanate potassium
- Clavulanic acid
- Clazosentan
- Clean Air Act
- Cleanser
- Clear cell
- Clear cell acanthoma
- Clear cell carcinoma
- Clear cell renal cell carcinoma
- Clear cell sarcoma
- Clear cell sarcoma of the kidney
- Clear-cell adenocarcinoma
- Clear-cell sarcoma
- Clear-cell sarcoma of the kidney
- Clearance
- Clearing the cervical spine
- Cleavage and polyadenylation specificity factor
- Cleavage furrow
- Clebopride
- Clec7a
- Cleft
- Cleft lip
- Cleft lip and palate
- Cleft lip with or without cleft palate
- Cleft palate
- Cleidocranial dysplasia
- Clemastine
- Clemizole
- Clenbuterol
- Clerodane diterpene
- Clevidipine
- Clevudine
- Clic2
- Clic6
- Client-centered therapy
- Climate change mitigation
- Climate psychology
- Climbazole
- Climbing fibers
- Clindamycin
- Clindamycin phosphate
- Cline
- Clinical Associate
- Clinical Opiate Withdrawal Scale
- Clinical Trials Directive
- Clinical attachment loss
- Clinical biochemistry
- Clinical clerkships
- Clinical data management
- Clinical death
- Clinical decision making
- Clinical decision support system
- Clinical dementia rating
- Clinical effectiveness
- Clinical electrophysiology
- Clinical endpoint
- Clinical equipoise
- Clinical examination
- Clinical formulation
- Clinical genetics
- Clinical guidelines
- Clinical imaging
- Clinical immunology
- Clinical information system
- Clinical laboratory
- Clinical medicine
- Clinical method
- Clinical microbiology
- Clinical negligence
- Clinical neurology
- Clinical neurophysiology
- Clinical neuropsychology
- Clinical pathology
- Clinical peer review
- Clinical pharmacists
- Clinical pharmacology
- Clinical pharmacy
- Clinical prediction rules
- Clinical protocols
- Clinical psychology
- Clinical research
- Clinical research associate
- Clinical research ethics
- Clinical significance
- Clinical social work
- Clinical study design
- Clinical supervision
- Clinical toxicology
- Clinical trials
- Clinical trials in India
- Clinical trials on Ayurveda
- Clinical trials unit
- Clinical virology
- Clinically isolated syndrome
- Clinician Administered PTSD Scale
- Clinician-Administered PTSD Scale
- Clinodactyly
- Clinoptilolite
- Clioquinol
- Clitoral
- Clitoral hood
- Clitoromegaly
- Clivus
- Cloacal
- Cloacal exstrophy
- Cloacal membrane
- Clobazam
- Clobenpropit