Defective/dɪˈfektɪv/ Definition 1 of 4Pro Tip 1/3Return Policy Understand when to use 'defective' in relation to warranties or guarantees for products. Check if your defective phone is covered by warranty. Pro Tip 2/3Negative Implication 'Defective' implies that something lacks essential functionality and is unsatisfactory. People often complain about defective electronics. Pro Tip 3/3Not Always Visible A defect may not always be visible; functionality tests can be necessary. Though it looked fine, the device was defective.