injective
|in/jec/tive|
/ɪnˈdʒɛktɪv/
distinct inputs → distinct outputs
Etymology
'injective' originates from Latin, specifically the word 'injicere', where 'in-' meant 'into' and 'jacere' (via the variant 'jicere') meant 'to throw'; the English adjective was formed from the verb 'inject' + the suffix '-ive'.
'injective' developed from Latin 'injicere' → Late Latin/Medieval Latin forms (e.g. 'injectio', 'inject-') → Old/Modern French 'injecter' and English 'inject' → English adjective 'injective' (formed in modern scientific/mathematical usage).
Initially related to the physical action 'to throw/put into' (i.e. to inject); over time the adjective specialized in mathematics to mean 'one-to-one' when describing functions.
Meanings by Part of Speech
Adjective 1
(mathematics) Of a function: one-to-one; a function f is injective if different inputs give different outputs (no two distinct elements have the same image).
An injective function maps each element of the domain to a distinct element of the codomain.
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Adjective 2
relating to or capable of being injected (rare; biological/medical usage).
The drug formulation was made injective for rapid administration.
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Last updated: 2025/10/09 04:31