The Spanish word 'esfinge' (meaning 'sphinx') comes from Latin 'sphinx', which in turn was borrowed from Ancient Greek 'σφίγξ' (sphinx). In Greek mythology, the sphinx was a legendary creature with the head of a human, the body of a lion, and sometimes the wings of a bird. The word maintained its meaning throughout its journey from Greek through Latin into Spanish, though its pronunciation and spelling adapted to Spanish phonological patterns, with the initial 's' becoming 'es' (a common Spanish adaptation of words beginning with 's' + consonant) and the 'ph' becoming 'f'.

While 'esfinge' doesn't have many common etymologically related words in Spanish, you might notice the same 'esf-' beginning in words like 'esfera' (sphere) and 'esfuerzo' (effort), though these come from different Greek roots. The 'es-' prefix in these words represents the same Spanish phonological pattern of adding 'e' before 's' + consonant clusters.

The English word 'sphinx' is directly related to Spanish 'esfinge', as they both come from the same Greek source 'σφίγξ'. English borrowed the word through Latin but kept a spelling closer to the original Greek. You can see how Spanish and English handled the Greek word differently: while English maintained the 'ph' spelling and final 'x', Spanish adapted it to its own spelling conventions with 'f' and '-e'.