A word in The Etymologies of the 1930s glossed “lying in bed, bedridden, sickness” derived from the root ᴹ√KAY “lie down” (Ety/KAY). In The Etymologies as published in The Lost Road (LR/363) the glosses were “lying in bed, sickness”, but in their Addenda and Corrigenda to the Etymologies Carl Hostetter and Patrick Wynne indicated that gloss “bedridden” appeared between “lying in bed” and “sickness” (EtyAC/KAL).

Neo-Sindarin: For purposes of Neo-Sindarin, I would assume cael is the noun (= “lying in bed, sickness”) and N. caeleb “bedridden, sick” is the adjective.