The warm, pleasant sensations one feels in the stomach and heart area when emotionally moved by an act of goodwill or love.

Watching children open presents on Christmas morning gives me the warm fuzzies.

Warming messages of friendliness or love to someone expressing a kind message to show gratitude toward one person or a whole group of people.

Warm fuzzy is singular for warm fuzzies

The opposite of warm fuzzy is a cold prickly.

"Congratulations to Ashley on her promotion! Everyone please, some applause and warm fuzzies for her!