What does crepitus mean?
Crepitus is a noun used almost entirely in medicine to describe a crackling, popping, or grating sound or sensation. Most people encounter it in relation to joints: the faint crunch felt or heard when a knee, shoulder, or other joint moves, which may be harmless or a sign of cartilage wear such as osteoarthritis. Clinicians also use the term more broadly — lung crepitus refers to the bubbling or crackling sounds heard through a stethoscope when air or fluid is present where it should not be, while subcutaneous crepitus describes the distinctive crackle felt under the skin when gas has escaped into soft tissue, a finding that can signal serious infection or injury. In orthopaedics, crepitus can refer specifically to the grating of fractured bone ends. Derived from Latin crepare, meaning to rattle or crackle, the word carries a precise, technical register: laypeople would simply say their knee 'crunches', but in a clinical note, crepitus conveys the finding economically and unambiguously.
nounA crackling or grating sound or sensation, especially the one produced by rubbing together the ends of a fractured bone, or by gas moving in the joints or lungs as heard through a stethoscope.
- A grating, crackling, or popping sound or sensation felt in a joint during movement, often associated with arthritis.
- The sound heard through a stethoscope of air or fluid crackling in the lungs (lung crepitus).
- A crunchy feeling under the skin caused by trapped subcutaneous gas (subcutaneous crepitus).
- The grating of broken bone ends against each other at a fracture site.
"The physician noted fine crepitus over the patient's lower ribs, a sign of the underlying fracture."
"Years of marathon running had left her with noticeable crepitus in both knees whenever she descended stairs."
"On auscultation, the resident detected coarse crepitus in the bases of both lungs."
Rarely used — crepitus normally functions as an uncountable noun, and clinicians describe different types or locations of crepitus rather than counting them.
"The report documented crepituses in several joints, each consistent with degenerative change."
That crunch you sometimes feel in your knees when climbing stairs has a name — doctors call it crepitus, from the Latin for 'a rattling'.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of crepitus
Crepitus comes directly from the Latin crepitus, meaning 'a rattling or crackling', derived from the verb crepare ('to rattle, crackle, or creak'). English adopted the word in the early modern period, likely via medical Latin. It shares this Latin root with words such as decrepit (originally 'grown old, worn out', literally 'noisy with age') and discrepant (from discrepare, 'to sound discordantly'), reflecting the root's consistent association with harsh or irregular sounds.
Related word forms
How crepitus is actually used
Crepitus is a formal, almost exclusively medical term. It appears in clinical documentation and specialist writing rather than everyday conversation, where speakers would more likely say 'cracking' or 'popping'. Plural usage is rare; the word typically functions as an uncountable mass noun describing a phenomenon rather than countable instances.
Easily confused with crepitus
"Crepitus" is the standard clinical term for the crackling sensation or sound itself, while "crepitation" is the more general act of crackling and is less commonly used in medical contexts.