Most dictionaries do separate fingers and thumb. They are all digits on the hand...but they are defined separately.
semantics - the bane of humanity.
the point is that any digit contact with a bowstring (but with some form of flexible digit protection material, like leather) still introduces more possibilities of string torque and bad releases than a real bowstring release aid. in most cases, using a "bare" thumb release takes as much if not more practice and skills than a spit, two, or three under finger release. none of this is a "release aid", it's as natural as can be.
Not arguing. I think thumb shooting tabs(not releases) should be allowed in all trad/barebow classes.
i absolutely agree for a thumb tab. it's just another padded digit that has all the issues of any digit applied to pulling back and releasing a bowstring.
but not a thumb ring - that's a ledge release aid.
as a side note, look at all the archery tournament equipment classes, it's mind boggling. this is what we had to contend with when setting up our local tournaments back in the 60's and 70's for having trophies on hand for awards, and to three places for each class.
stickbow barebow fingers - men
stickbow barebow fingers - women
stickbow barebow fingers - under 18 male
stickbow barebow fingers - under 18 female
stickbow barebow fingers - under 12 male
stickbow barebow fingers - under 12 female
stickbow fingers limited (bowsight) - men
stickbow fingers limited (bowsight) - women
stickbow fingers limited (bowsight) - under 18 male
stickbow fingers limited (bowsight) - under 18 female
stickbow fingers limited (bowsight) - under 12 male
stickbow fingers limited (bowsight) - under 12 female
stickbow unlimited (bowsight and release aid) - men
stickbow unlimited (bowsight and release aid) - women
stickbow unlimited (bowsight and release aid) - under 18 male
stickbow unlimited (bowsight and release aid) - under 18 female
stickbow unlimited (bowsight and release aid) - under 12 male
stickbow unlimited (bowsight and release aid) - under 12 female
and if yer club also included wheelbows, yikes!!