Definition of "luke"

Let me have nine penn'orth o' brandy and water luke, and the inkstand, will you, miss?

1836, Charles Dickens, The Pickwick Papers

Then one of them turned coward on account of the exceeding chill,cast away his faith, and desired to bathe himselfin the luke water, and turned from his companions;but he died as soon as he touched the water,and the warmness was turned into death to him […]

1881, Ælfric, trans. Walter W. Skeat, Aelfric’s Lives of Saints, page 249

Next thing, I have a confrince with Barry and I tells him, 'Frankly, kid, it don't look any too hot over there at Regal. In fack, very luke.'

1946, Arthur Kober, That Man is Here Again: The Adventures of a Hollywood Agent, Random House

Secondly, fresh, preferably luke to warm water must be provided in waterers every day to avoid dehydration, weakening and ‘going light’. […] Warm to luke water is given in waterers as an alternative because all fowl drink more water if it is not excessively cold, […]

1983, C. Darrel Sheraw, Lou Horton, Bill Durbin, The Call Duck Breed Book, page 106

Same time, if you put the other hand in cold water and then in luke water, you will feel luke warm water is hot.

2016, Ankur and Vandana Mehrotra, You Can Do It: Find Answers to All Your Questions on How to Become a Successful Entrepreneur Now