Abarim Publications' online Biblical Hebrew Dictionary
The verb רצה (rasa) means to be pleased with, be favorable to, or accept favorably. HAW Theological Wordbook of the Old Testament reports that this verb is a "very ancient West-Semitic root," found in many cognates, in a letter from Amarna (1370 BC) and all over the Bible. This verb is used to indicate God's response towards the Servant (Isaiah 42:1) or of people to people (Malachi 1:8). It's used to indicate acceptability of offerings to God (2 Samuel 24:23), to indicate sadism (Psalm 40:14), or to enjoy rest like a Sabbath (Leviticus 26:34).
This verb comes with one derivative, namely the masculine noun רצון (rason), meaning goodwill, favor, pleasure of acceptance (Deuteronomy 33:16, Exodus 28:38, Ezra 10:11).