Source : Webster's Revised Unabridged Dictionary (1913)

Leptomeningitis \Lep`to*men`in*gi"tis\
   (l[e^]p`t[-o]*m[e^]n`[i^]n*j[imac]"t[i^]s), n. [NL., fr. Gr.
   lepto`s small + meningitis.] (Med.)
   Inflammation of the pia mater or of the arachnoid membrane.

Source : WordNet®

leptomeningitis
     n : inflammation of the leptomeninges