Etymology
I have identified three words which might help to explain Walker and Bunting's terms.
1 Fuáil (feminine) = fuaigheal
The verbal noun 'fuáil' (sewing) was spelled variously in the past and would relate to the
spellings 'fuigheall', 'fuaidhghel' & 'fuaidhghail' given by Walker/Beauford and perhaps
'fuadhghail' which appears in MS37.
The words spelled anciently 'úaimm', 'úaigél' and 'fúaigél' all mean stitching, sewing or a
seam; also uniting, welding, joining together. The verb from which they derive, 'úaigid',
also has the additional meaning 'to weave' and, figuratively, to weave words, as did the
verb 'figid'.
2 Fuíoll (feminine) = fuígheall
This word may derive from the feminine noun 'faíd' (cry), which was used in relation to the
voice of humans (especially in lamentation), of animals (especially birds) and of bells or
musical instruments. In a wider sense it refers to the speaking or singing voice as per the
word 'faoí' (voice/sound).
The spelling 'faídél' is not attested in ancient literature: only the nouns 'faídech' and
masculine 'faídiud' (lamenting) and adjective 'faídemail' (prophetic).
However, O' Brien's Foclóir Gaoidhilge Sax-Bhéarla of 1768 contains the word 'fuígheall'
(word), plural 'fùighle' (words or expressions). The Dictionary of the Irish Language also
gives the (perhaps feminine) ancient word 'fuigell' (judgement/verdict/sentence) with the
plural 'fuighle' (words), seen in the phrase 'fuighle naomh' (prophecy).
3 Fuíoll (masculine) - remnant, remainder = fuígheall
3 Fuílleach (masculine) - remnant, remainder = fuíghleach
These words may derive from the ancient verb fo-díla (to remain, remain over) and relate
to the nouns 'fuidel' and 'fúait' (remnant/remainder). These words also had the meaning
of 'outcome/result' which could, in reference to the Gaelic harp, refer to the finished
tuning after the process of tuning up. The term would sound very strange in direct
translation to English and is very idiomatic in Gaelic.