There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.
sinde
adjective. grey, pale
sin(de)
adverb. so, so much, *of this degree
sin(an)
adverb. now, at present
hiswa
adjective. grey, grey [of weather], *foggy, overcast; [ᴱQ.] dim, fading
This word is glossed “grey” in The Etymologies, but perhaps means “✱foggy, overcast”, since Sindarin cognate hethw means “foggy, obscure, vague” and related noun hiswë means “fog”. @@@
Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.
A correlative appearing as sinan or (archaic) †sin in Demonstrative, Relative, and Correlative Stems (DRC) from 1948 (PE23/109), a combination of ᴹQ. si “this” and ᴹQ. -n(an) “time”. Sinan was translated as “at present” in the Quenya Verbal System (QVS) of this same period (PE22/125).