"Lamenting" essentially means expressing deep sadness or sorrow, usually through mourning, grieving, or feeling regretful about something. Full definition
God of War was a rip off of Lament of Innocence and that was a Castlevania game that came out before God of War. (blog.us.playstation.com)
Instead of lamenting about being up + $ 250 in the morning only to finish a choppy afternoon at - $ 150 before trade costs, quit while acceptably ahead. (tradingmarkets.com)
Deadpool also lamented for loss of teaching cursive in the American educational system. (filmfestivaltoday.com)