Strong's H387 is the proper name Ethan (אֵיתָן), used specifically for the named individuals in the biblical text — distinct from the adjective form (H386). Several men bear this name in the Old Testament: the Ezrahite sage who authored Psalm 89, a Levitical musician in David's court, and others in genealogical records.
Ethan the Ezrahite's authorship of Psalm 89 is theologically significant because the psalm grapples honestly with apparent covenant failure — David's dynasty seemed imperiled — yet ends in confident praise and supplication. The name ethan (perennial, constant) is fitting for a man who clung to God's unchanging faithfulness even in distress. In David's worship organization, Ethan son of Kushaiah was one of the chief musicians assigned to the bronze cymbals (1 Chronicles 15:17–19), appointed to lead Israel in praise before the ark of God.