Sindarin 

thol

sōl

pl1. thely or thuil _n. _Q. sōl. >> castol

Sindarin [(PE17 Sindarin Corpus) PE17:188] < ÞOL stand up, 'top'. Group: Parma Eldalamberon 17 Sindarin Corpus. Published by

thol-

verb. to roll

-eb

suffix. adjective suffix

Sindarin [WJ/337; WJ/412] Group: Eldamo. Published by

-en

suffix. adjective suffix

Sindarin [PE17/098; RGEO/62; SA/lin¹; SD/129] Group: Eldamo. Published by

-iel

suffix. adjective suffix

-in

suffix. adjective suffix

-ren

suffix. adjective suffix

@@@ perhaps a later, S-only, innovation