IPA: /ˈɪnɡreɪt/
KK: /ˈɪnˌɡreɪt/
A person who does not show gratitude or appreciation for something they have received.
Despite all the help she received, he remained an ingrate and never thanked anyone.
Ingrate → It is formed from "in-" (meaning not) and "gratus" (meaning pleasing or thankful). The word describes someone who is not thankful or appreciative.
Think of someone who is 'not' ('in-') 'thankful' ('gratus') — that's why an ingrate is someone who does not show gratitude.