Sanskrit

Noun

मर्मन् • ‎(márman)

1. mortal spot, vulnerable point, any open or exposed or weak or sensitive part of the body (in Nir. reckoned to be 107) (RV. etc.)
2. the joint of a limb, any joint or articulation (ib.)
3. the core of anything, the quick (ib.)
4. any vital member or organ (compare अन्तर्मर्मन् ‎(antar-marman))
5. anything which requires to be kept concealed, secret quality, hidden meaning, any secret or mystery (MBh., Kāv. etc.)

References

• Sir Monier Monier-Williams (1898) A Sanskrit-English dictionary etymologically and philologically arranged with special reference to cognate Indo-European languages, Oxford: Clarendon Press, page 0791