Quenya 

urda

adjective. hard, difficult, arduous, difficult, arduous, hard

An adjective appearing in Definitive Linguistic Notes (DLN) from 1959 glossed “hard, difficult, arduous” based on the root √GUR of similar meaning (PE17/154).

Neo-Quenya: I believe that urda has a connotation of “difficult, arduous” due to the inherent complexity or difficulty of the task, as opposed to hraia or hranga meaning “difficult, hard” due to resistance from the thing or people being worked upon.

urda

hard, difficult, arduous

urda adj. "hard, difficult, arduous" (PE17:154)

sarda

hard

sarda adj. "hard" (VT39:17); pl. sardë "hards" may be used in the same sense as sarda tengwi, q.v. (As an independent form we would rather expect a nominal pl. sardar.)

torna

hard

#torna adj. "hard", as in tornanga (q.v.), seemingly -storna after prefixes ending in a vowel, as in the comparative forms aristorna, anastorna (PE17:56; the forms are untranslated and may not necessarily be the same adjective "hard".)

torna

adjective. hard