well

before 900; Middle English, Old English wel(l) (adj. and adv.); cognate with Dutch wel, German wohl, Old Norse vel, Gothic waila

Sometimes an adverb like well is so often placed in front of and combined with a certain past participle in order to modify it that the resulting adjectival combination achieves the status of a common word and is listed in dictionaries. In Dictionary.com you will find, for example, entries for well-advised and well-mannered; for ill-advised, ill-bred, and ill-conceived; and for half-baked and half-cocked. Some of these terms are given full definitions, while others are considered such obvious combinations that you can figure out for yourself what they must mean. It is important to note, however, that compound adjectives like these are hyphenated for use before the noun they modify together. Thus we say that someone is “a well-loved professor,” but there would be no hyphen between well and loved in a sentence like “My English professor is well loved and deserves the award.”
In a similar manner, adjectival compounds formed with better, best, little, lesser, least, etc., are also hyphenated when placed before the noun ( a little-understood theory ), but the hyphen is dropped when the adjectival combination follows the noun ( his films are best known in England ) or is itself modified by an adverb ( a too little understood theory ).
There are exceptions to this pattern. For example, when the combining adverb ends in –ly, no hyphen is required, whether the resulting adjectival combination appears before or after the noun: a highly regarded surgeon; a surgeon who is highly regarded.
Don’t let the hyphens fool you. Punctuation can be tricky!

See good.

before 900; (noun) Middle English well(e), Old English wylle, wella, welle; cognate with German Welle wave; (v.) Middle English wellen, Old English wellan (cognate with Dutch wellen, Old Norse vella); both noun and v. ultimately akin to weallan to boil

See contraction.