1. having a defect or flaw; faulty; imperfect: a defective machine.
  2. Psychology. characterized by subnormal intelligence or behavior.
  3. Grammar. (of an inflected word or its inflection) lacking one or more of the inflected forms proper to most words of the same class in the language, as English must, which occurs only in the present tense.
  1. a defective person or thing.

Origin of defective

1375–1425; < Late Latin dēfectīvus, equivalent to dēfectus (see defect) + -īvus -ive; replacing Middle English defectif < Middle French < Late Latin, as above
Related formsde·fec·tive·ly, adverbde·fec·tive·ness, nounnon·de·fec·tive, adjectivenon·de·fec·tive·ly, adverbnon·de·fec·tive·ness, nounpre·de·fec·tive, adjectiveun·de·fec·tive, adjectiveun·de·fec·tive·ly, adverbun·de·fec·tive·ness, noun

Synonyms for defective

Antonyms for defective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for non-defective


  1. having a defect or flaw; imperfect; faulty
  2. (of a person) below the usual standard or level, esp in intelligence
  3. grammar (of a word) lacking the full range of inflections characteristic of its form class, as for example must, which has no past tense
Derived Formsdefectively, adverbdefectiveness, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for non-defective



mid-14c., from Middle French défectif (14c.) and directly from Late Latin defectivus, from defect-, past participle stem of deficere (see deficient). A euphemism for "mentally ill" from 1898 to c.1935. Related: Defectively; defectiveness.

Online Etymology Dictionary, © 2010 Douglas Harper

non-defective in Medicine


  1. Having an imperfection or malformation.
  2. Lacking or deficient in some physical or mental function.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.