Where does “rockhearted” come from?

rockhearted (English) comes from English Rock, from English rock and roll, from English and, from Middle English an, from Old English ond, from Old English and, from Proto-Germanic andi, from Proto-Indo-European h₂énti — on, onto.

Ancestry of “rockhearted”, step by step

rockhearted traces back through two separate lines of ancestry.

via English Rock

StepLanguageWordMeaning
1EnglishRockfor someone living near a rock or an oak (atter + oke)
2Englishrock and rollA genre of popular music that evolved in the...
3EnglishandAs a coordinating conjunction; expressing two...
4Middle EnglishanAlternative form of in; Alternative form of and;...
5Old Englishondand
6Old Englishandand; even; also
7Proto-Germanicandiin addition, furthermore, and
8Proto-Indo-Europeanh₂éntiopposite; near; in front
9Proto-Indo-Europeanh₂éntsforehead; front
10Proto-Indo-Europeanh₂ent-face; forehead; front
11Proto-Indo-Europeanh₂en-on, onto

via English hearted

StepLanguageWordMeaning
1Englishheartedsimple past tense and past participle of heart;...
2Middle EnglishhertedHaving a specified disposition, emotion, or...
3Middle EnglishherteThe heart; One's inner self; the mind or...
4Old Englishheorteheart
5Proto-West Germanichertāheart
6Proto-Germanichertôheart
7Proto-Indo-Europeanḱḗrheart
Every word from Proto-Indo-European h₂en-
rockhearted — Etymology, Origin & Word History | Etymology Explorer