sanar noun "mind" (literally "thinker" or "reflector", suggesting an underlying verb #sana- "to think, to reflect") (VT41:13)
Primitive elvish
in(id)
root. mind, (inner) thought, inmost heart, inner senses
Quenya
indo
noun. (state of) mind, (inner) thought, mood; will, resolve, (state of) mind, (inner) thought, mood; will, resolve; [ᴹQ.] heart
sanar
mind
sáma
mind
sáma noun "mind" (pl. sámar and dual samat [sic, read *sámat?] are given) (VT39:23, VT41:5, VT49:33, PE17:183)
sáma
noun. mind
síma
mind, imagination
síma noun "mind, imagination" (VT49:16); variant isima. Also attested with endings: símaryassen "in their imaginations" (with the ending -rya used = "their" rather than "his/her", according to colloquial useage) (VT49:16)
Sindarin
gûr
inner mind
(i ’ûr, construct gur) (heart), pl. guir (i nguir = i ñuir). Note: A homophone means ”death”, but has different mutations. (VT41:11)
ind
mind
ind (inner thought, meaning, heart), no distinct pl. form;, coll. pl. innath.
ind
mind
(inner thought, meaning, heart), no distinct pl. form;, coll. pl. innath.
A root appearing in various notes written around 1957 connected to the mind (PE17/145, 155, 189; UT/400; VT43/16). Its most notable derivatives are Q. indo/S. ind “(state of) mind”. In The Etymologies of the 1930s, ᴹQ. indo “heart, mood” and N. ind “inner thought, meaning, heart” were instead derived from the root ᴹ√ID; this 1930s root was unglossed but had derivatives connected to both thoughts and desires, such as ᴹQ. íre “desire, longing” (Ety/ID).
Tolkien introduced a new derivation of indo from √IN(ID) in Quenya Notes written in 1957 (PE17/145, 189):
> IN-I-D, mind, inner thought. These refer to the movements or activities of the fëa or “spirit” (rational soul). indo, inner thought, in fea as exhibited in character or [?personality]. indóme, settled character, also used of the “will” of Eru (PE17/189).
The root √IN- “inmost heart, thought, mind” with extended forms √INID and √INIS also appeared in contemporaneous Notes on Names (NN), again as the basis for indo (PE17/155).
Tolkien coined yet another etymology of Q. indo in notes written in 1969, deriving it from √NID “force, press(ure), thrust” (PE22/165). This new derivation doesn’t necessarily invalidate √INID, but rather gives a new basis for the root itself as an vocalic augment of √NID rather than an extended form of √IN-.