An antonym is a word that has the opposite meaning of another word. In this case, 'querulous' refers to someone who is habitually complaining or whining, while 'easygoing' describes someone who is relaxed and not easily upset. 'Impeccable' means flawless or perfect, making 'imperfect' its direct opposite. Lastly, 'indigenous' refers to something native to a particular place, while 'foreign' indicates something that comes from outside that place. Understanding antonyms helps in expanding vocabulary and improving language skills.