IPA: /ʌnˈpɜːrsɛptɪv/
KK: /ʌnˈpɜrˌsɛptɪv/
Not able to notice or understand things easily; lacking insight or awareness.
He was often unperceptive to the feelings of others, missing subtle cues in conversations.
Unperceptive → It is formed from "un-" (meaning not) and "perceptive" (from Latin "perceptivus", meaning able to perceive). The word "unperceptive" means not able to perceive or lacking in perception.
Think of 'not' ('un-') being added to 'able to perceive' ('perceptive') — this helps you remember that unperceptive means lacking the ability to notice or understand.