A loud vocal expression — either joyful shouting or desperate crying out. The same word covers the shout of joy at harvest and the cry of anguish in suffering. Context determines which.
The range of rinnah from joy to lament reflects how deeply felt emotion is expressed the same way — loudly, whole-heartedly. God hears the rinnah of both suffering and celebration.
Psalm 30:5's famous contrast — weeping at night, joy (rinnah) in the morning — makes rinnah the emotional sunrise after grief. It frames the entire Psalter's movement from lament to praise.