dobber

listen to the pronunciation of dobber
Englisch - Englisch
A large marble
A member of the working class in Scotland who is seen as under-educated; to have poor taste, especially in their choice of clothes; and to have poor social skills. Closely related to the English chav
Small electronic device that plugs directly into a larger electronic device. E.g: Wireless scoring systems (fencing), USB mass storage devices, etc. Etymology: The word originally referred only to Electronic Coaching aids; small scoring devices that are plugged directly into the fencing foil or epee and used for basic scoring instead of the larger scoring machines. However, its use has since spread into more general areas of technical vocabulary, becoming particularly popular in the BBC Radio Online and IT departments
A float (as used by an angler)
A tool used to play Bingo
One who dobs, that is, informs against or implicates others to authority

Nicky is such a dobber, she told the teacher that I hit Karen in the playground.

A float to a fishing line
{i} fishing line float; tattletale, informer (Informal); dabchick, type of small grebe (Zoology)
cobber-dobber
{i} (slang used in Australia and New Zealand) person who dobs on a friend, one who informs against a mate