Jakob Jakobsen, An Etymological Dictionary of the Norn Language in Shetland…
“ When milking the cow, some drops of milk were sprinkled on the “bosten” in the byre; likewise at a private baptism, the “bosten” was sometimes sprinkled with a few drops of the baptismal water. 2) a sea-term, tabu-name in fishermen’s language for the sinker (kappi) on the fishing hand-line or long-line. Conn. — Meaning 1 is doubtless the original one, and meaning 2 derived from the former, as a certain faith and sense of consecration were associated with the sinker, as well as with the actual “bosten”. A successful sinker was thought to bring good luck when used in fishing. ”
