The word for the “heart” as a physical organ, as opposed to more metaphorical words like Q. órë and Q. indo. Its stem form was hom- in Tolkien’s later writings (NM/176, PE19/97).
Conceptual Development: The base word for “heart” was quite stable in Tolkien’s mind, but its exact stem form varied. It first appeared as ᴱQ. hon (hond-) “heart” in the Qenya Lexicon of the 1910s under the early root ᴱ√HONO, above a longer form hondo (QL/40). It became honde “heart” in Early Qenya Word-lists of the 1920s (PE16/137), but in the contemporaneous Early Noldorin Word-lists, it was londo (PE13/149, 162).
In the Declension of Nouns from the early 1930s it was ᴹQ. hón “heart” with stem form hom- (PE21/23), but in The Etymologies written around 1937 it was derived from the root ᴹ√KHŌ-N “heart (physical)” (Ety/KHŌ-N). In 1968 notes on gender, hón the “physical organ heart” again had a stem form hom-, and in green ink addendums to the Outline of Phonology (OP2) from around 1970, Tolkien gave the primitive form as ✶khō̆m (PE19/97 and 98 note #142). In this last note, Tolkien said it “is not the physical heart, but ‘the interior’ used of the whole range of emotions or feelings”; this seems to be the only place Tolkien indicated this word was metaphorical in nature rather than referring to the physical organ.
hón noun "heart" (physical) (KHŌ-N); hon-maren "heart of the house", a fire (LR:63, 73; this is "Qenya" with genitive in -en, not -o as in LotR-style Quenya read *hon-maro?)