The RAE (similar to the Oxford Dictionary in English) includes ‘por qué’ as an adverbial phrase under the entry for ‘por’ meaning “for what reason, cause or motive”. ‘Porque’ is a conjunction that translates to “because”. And for fun, ‘porqué’ is a noun, similar to how in English you ask about “the why” or reason behind or for something. ‘El porqué’ would be “the answer” to the question ‘¿por qué?’
One phrase, but two words. Its less analogous to why and more like "because of/for what". In English its just one word but in Spanish its actually a phrase. Funnily enough, porque means because and is one word. To make matters worse there's also porqué and por que which mean slightly diferentes things