The Tigers had gone unbeaten in three matches going into Saturday’s KCOM encounter, but they remain in deep relegation trouble with only Ipswich Town below them in the Championship table.
Aitor Karanka’s Nottingham Forest controlled the game for long periods, with perhaps the biggest surprise being that they did not score in the first half.
But once Lewis Grabban seized upon a desperate mistake from Hull defender Jordy De Wijs after 61 minutes, the game was effectively over.
Joe Lolley doubled Forest’s lead just three minutes later – albeit via a deflection – but the scoreline could have been much more emphatic had Hull goalkeeper David Marshall not produced a string of fine saves late into the game.
Adkins felt De Wijs’s error was the decisive moment of the match.
“We’ve gifted them the opportunity to win the game and they have gone and capitalised on that,” said the Tigers’ manager.
“It’s very frustrating. It’s another shocking goal from an individual mistake and then they get a deflection (for the second goal).
“It’s fair to say they got too much possession of the football for my liking in the first half.
“We started the second half well but it (Forest’s opening goal) was from our cross and then they’ve countered the length of the pitch.
“All of a sudden, the game that you are in goes against you.
“I was very disappointed with our final half (an hour) – we were nowhere near where we need to be.
“But you’ve got to give Forest credit as they passed the ball well.
“There was a good spirit going into the game – a desire to do well – but goals do change the complexion of things.”
A delighted Karanka said he was pleased to see the continuing development of his Forest team.
“We are showing we are still improving and I’m really pleased,” he said.
“We want to keep growing and with this quality on the pitch we can do nice things. The main thing for me is that I can feel the improvement every single game.”
Hull City: Marshall, Burke, Elphick, De Wijs, Lichaj, Bowen, Batty (Kane 62), Irvine (Keane 86), Grosicki, Campbell, Martin (Stewart 46). Unused substitutes: Mazuch, Long, Sheaf, McKenzie.
Nottm Forest: Pantilimon, Darikwa, Dawson, Figueiredo, Robinson, Colback, Yacob, Cash (Osborn 82), Joao Carvalho, Lolley, Grabban (Ansarifard 86). Unused substitutes: Guedioura, Steele, Janko, Gil Dias, Hefele.
Referee: Graham Scott (Oxfordshire).