This root was associated with craft and skill for much of Tolkien’s life. The earliest iteration of the root was unglossed ᴱ√KURU whose Qenya and Gnomish derivatives mostly had to do with magic, such as ᴱQ. kuru “magic, wizardry” and G. curu “magic” (QL/49, GL/28). It appeared again in The Etymologies of the 1930s as ᴹ√KUR “craft” with derivatives like ᴹQ. kurwe “craft” and N. curu “cunning”. It was mentioned again in notes associated with The Shibboleth of Fëanor from 1968 with the gloss “skill” and various derivatives similar to the 1930s. Its final mention in published material is from Late Notes on Verbs from 1969:
> “can” = have power, strength, ability inherent physically or mentally. √KURU. Cf. ✱kurwē “power, ability”, S curu in curunír “wizard”, us[ually] applied to exceptional powers espec. of mind, ability to make one’s will effective. It thus approaches some uses of our “magic”, esp. when applied to powers not understood by the speaker, but it does not even then (except perhaps when the word was used by Men) connote any alteration or disturbance of the “natural order”, which to the Eldar were either “miracles” performed by agents of the One or counterfeits by delusion (or by means other than miraculous which impressed the uninstructed as supernatural) (PE22/151).
This last note reconciles the connection between this root and “magic”, in that some powers of the mind that Elves perceive as natural skill would seem to Men to be magical, and in this sense it is the basis for words like S. curunír “wizard”.
A noun translated as “strength, endurance, fidelity”, and used as an example of noun declension in Lowdham’s Report (SD/431). Carl Hostetter and Patrick Wynne suggested (AAD/9) that it may be related to the Elvish root ᴹ√BOR(ON) “endure”. It may also be related to the name Abrazân “✱Steadfast, Faithful”.
Conceptual Development: This word also appeared in earlier Adûnaic names Zen’nabâr and Abarzâyan (both glossed “Land of Gift”), where it apparently had the meaning “gift”. These names were eventually replaced by Yôzâyan in which the element yô means “gift”, freeing abâr to have the meaning: “strength, endurance, fidelity”.