tyar- vb. "cause" (KYAR)
Primitive elvish
kah
root. cause
Quenya
casta
cause
tyar-
cause
tyar-
verb. cause
Beware, older languages below! The languages below were invented during Tolkien's earlier period and should be used with caution. Remember to never, ever mix words from different languages!
Early Primitive Elvish
kahta
noun. kahta
kaha
root. cause
A root in the Qenya Lexicon of the 1910s glossed “cause” with derivatives like ᴱQ. ka- “cause”, ᴱQ. káma “guilt, responsibility”, and ᴱQ. kasta “cause, motive, ultimate reason” (QL/43). There are similar derivatives in the contemporaneous Gnomish Lexicon, such as G. caith “cause, reason, motive” < ᴱ✶kahta (GL/24). Some of these words have no good replacements in Tolkien’s later writing, so I think it is worthwhile to postulate a Neo-Eldarin root ᴺ√KAH to salvage some of these early words.
Early Quenya
ka-
prefix. cause
casta (2) noun "cause" (reason) (QL:43)