Both well and good are adjectives when they follow feel to express a meaning of good health, and both are grammatically correct. In "I feel good" there is often a connotation of good spirits in addition to …

Well is a discourse marker, adverb or adjective. … In speaking, we often use well at the start of what we say. Its main function is to show that we are thinking about the question that we have been asked: …

In a good or proper manner: behaved well. 2. Skillfully or proficiently: dances well.

She is good at softball as well as basketball. You might as well tell them the truth.

a container, receptacle, or reservoir for a liquid: the well of ink in a fountain pen. Building any sunken or deep, enclosed space, as a shaft for air or light, stairs, or an elevator, extending vertically through …

You use well in front of a prepositional phrase to emphasize it. For example, if you say that one thing happened well before another, you mean that it happened a long time before it.

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 …