The noun aresheth appears only once in the Old Testament (Psalm 21:2), meaning the request or desire of the heart. It describes what a person deeply yearns for — the inner longing brought before God in prayer.
Though rare, aresheth appears in a royal Psalm celebrating God's faithful provision for the king. The context establishes the theological principle that God answers the heartfelt requests of those who trust Him — 'You have not withheld the request of his lips.' This connects to the broader biblical teaching that God hears prayer, knows our desires before we ask, and delights to fulfill the requests of the righteous.