lockjaw
UK[ˈlɒkdʒɔː]US[ˈlɑːkdʒɑː]
n
A condition in which the jaw muscles become stiff and the mouth is difficult to open, especially as a symptom of tetanus.
Morpheme Breakdown
lock
jaw
lock
to make fast or rigid.
jaw
Etymology
The term 'lockjaw' is a transparent English compound, formed by combining the verb 'lock', implying a mechanism of rigid fastening, with the noun 'jaw'. It is a descriptive, colloquial name for the medical condition trismus, a hallmark symptom of tetanus infection. The logic is vividly metaphorical: the jaw muscles undergo such severe spasms that the mouth seems mechanically locked shut. This compound exemplifies how English creates accessible terminology by pairing familiar, concrete words to describe a specific and often frightening physiological state.
Analysis
Structure: lock + jaw
lock: From Old English loc (fastening, enclosure), of Germanic origin. In this compound, it functions as a verb-derived element meaning "to make fast or rigid."
jaw: From Middle English jawe, jowe, of uncertain origin but likely from Old French joe (cheek). It functions as the noun denoting the anatomical part.
Examples
The first symptom of tetanus is often lockjaw, making it hard to swallow or open the mouth.
After the rusty nail injury, he was given a tetanus shot to prevent the risk of developing lockjaw.
The doctor diagnosed the persistent jaw stiffness as a case of lockjaw.