meninx vs leptomeninges

meninx and leptomeninges both are nouns.

Word	Noun	Adjective	Verb	Adverb
meninx	Yes	No	No	No
leptomeninges	Yes	No	No	No

As nouns, leptomeninges is a hyponym of meninx; that is, leptomeninges is a word with a more specific, narrower meaning than meninx:

meninx: a membrane (one of 3) that envelops the brain and spinal cord
leptomeninges: the two innermost layers of the meninges; cerebrospinal fluid circulates between these innermost layers

Other hyponyms of meninx include dura, dura mater, arachnoid, arachnoid membrane, pia mater.

meninx (noun)	leptomeninges (noun)
a membrane (one of 3) that envelops the brain and spinal cord	the two innermost layers of the meninges; cerebrospinal fluid circulates between these innermost layers