In American English, yes, it is one word. In British English it is hyphenated as kind-hearted.
It is one word because you can search it in the dictionary and it will go as kindhearted
Kindhearted
No, kindhearted (single compound word) is an adjective, a word that describes a noun; for example, a kindhearted person, a kindhearted gesture.
Three.
Caring, kindhearted,
kindhearted
The word "hearts" has one syllable.
kindhearted
Kindhearted is a nice word. Knowledgeable is a nice word.
Keen, kind, kindhearted and knowledgeable are nice words to describe a person. They begin with the letter k.
· keen · kind · kindhearted · knowledgeable
Kindhearted and knowledgeable are kind words.