a small amount of something, something of a meagre quantity.
Honestly officer im not drunk,ive only had a fartsworth.
look at how small that kitten is, hes not even a fartsworth.
the awful smell of a persons bad-breath, often during early morning, or last thing at night, an often terrible whiff of a bad stench,
Jeez, did you smell the breath of her, it smelt like she had been eating shit butties,