Definition of "undelightful"

[Y]our Harriet may turn gadfly, and never be eaſy but vvhen ſhe is forming parties, or giving vvay to them, that may make the home, that hitherto has been the chief ſcene of her pleaſures, undelightful to her.

1753 (indicated as 1754), [Samuel Richardson], “Letter XVIII. Miss Byron. In Continuation.”, in The History of Sir Charles Grandison. […], 2nd edition, volume I, London: […] S[amuel] Richardson; [a]nd sold by C. Hitch and L. Hawes, […], page 125

Every trick that money can play with the most lavish abundance of water is here exhibited; nor is the sight of a jet d'eau, or the murmur of an artificial cascade, undelightful in a hot day, let the Nature-mongers say what they please.

1789, Hester Lynch Piozzi, Observations and Reflections Made in the Course of a Journey through France, Italy, and Germany, Vol. I‎

However, ironically, it has also been pointed out that until the excess of nutrients in the upper estuary is eliminated, such clearing of the water could very possibly cause a great increase in the already disastrous algae blooms, by allowing sunlight to penetrate to greater depths and foster more production of this undelightful greenery.

1968, United States Department of the Interior, The Nation's River‎