FullDefinition

FullDefinition[symbol] prints as the definitions given for symbol, and all symbols on which these depend.

FullDefinition["symbol"] prints as the definitions given for the symbol named "symbol" if it exists, and all symbols on which these depend.

FullDefinition[patt] prints as the definitions given for the symbols whose names textually match the arbitrary string pattern patt, and all symbols on which these depend.

FullDefinition[{spec1,spec2,…}] prints as the definitions given for the symbols that are equal to or whose names match any of the speci, and all symbols on which these depend.

Please visit the official Wolfram Language Reference for more details and examples on core symbols.