The musical instrument
takes it name from the Arabic word
in Arabic script.
The definite article al has become part of the word in the other languages. The sound I transcribe here by ` is a pharyngal voiced approximant.
Dictionary of Modern Written Arabic, by Hans Wehr, edited by J M. Cowan,
has these meanings:
wood; stick, rod, pole; branch, twig, switch; stem, stalk; cane, reed; aloes (wood); lute (musical instrument); body, build, physique; strength, force, intensity;
In Portuguese fado music, the word guitarra is reserved for the Portuguese guitar , whereas what in most other languages is a guitar is referred to as viola. This has nothing to do with a bigger and lower sounding type of violin, which is what the word viola means in other languages.
Interestingly, Spanish has the cognate word vihuela, which also denotes a guitar-like shaped instrument. The Portuguese word viola, says the Porto Editora dictionary, derives from Provençal viula. Provençal, Occitan or Langue d'Oc was the language of the troubadours, the minstrels, but not the bards.