Mid 16th century; earliest use found in 2nd Baron Berners (c1467–1533), soldier, diplomat, and translator. From well + thought, past participle of think + on.
Definition of well-thought-on in US English:
well-thought-on
adjectiveˌwɛlˈθɔːtɒn
Well-thought-of. Now archaic or regional.
Origin
Mid 16th century; earliest use found in 2nd Baron Berners (c1467–1533), soldier, diplomat, and translator. From well + thought, past participle of think + on.