Primitive elvish
kelu
verb. well forth, begin to flow
kelumē
verb. kelumē
kelu-
verb. to well up, flow (out swiftly), well forth
kelutā-
verb. to cause to spring forth, start (water) flowing, tap
kelus
noun. brook
sir
root. flow
sirya-
verb. to flow, to flow [smoothly]
sīru
noun. stream
The root √SIR and similar roots meant “flow” for most of Tolkien’s life. The earliest form of this root was ᴱ√SIŘI [SIÐI] “flow” in the Qenya Lexicon of the 1910s with variant sini and derived forms like ᴱQ. sindi “river” and ᴱQ. síre “stream” (QL/84). The latter word became “river” in Tolkien’s later writings, and words appearing in the contemporaneous Gnomish Lexicon like G. sîr “river” and G. siriol “flowing” (GL/67-68) rather than ✱✱sidh- indicate Tolkien very early revised the root to ✱ᴱ√SIRI. Indeed, the root was ᴹ√SIR “flow” in The Etymologies of the 1930s, and the root appeared with this form and essential meaning several times in Tolkien’s later writings (PE22/127, 135).