A noun for “juice” appearing in 1970 green-ink revisions to the Outline of Phonology (OP2), derived from ✶negdē “exudation” based on the root √NEG “ooze, drip”; its Quenya cognate was Q. nehtë “honey” (PE19/91). Sindarin nîdh was a later iteration of N. {nēdh >>} nīdh “honeycomb” in The Etymologies of the 1930s which had essentially the same derivation (EtyAC/NEG). This in turn was a later form of G. nectha “honey comb” in the Gnomish Lexicon of the 1910s (GL/60), cognate to ᴱQ. nekte “honey” and hence derived from the early root ᴱ√NEHE having to do with bees and honey (QL/65).
Neo-Sindarin: For purposes of Neo-Sindarin, I’d use nîdh with its earlier meaning “honeycomb”. For “juice” I’d use other words like [N.] saw and [ᴺS.] paich (adapted from N. peich).
juice