tattletale

noun

1. a talebearer or informer, especially among children.

adjective

2. telltale; revealing: a tattletale smear of lipstick on his collar.

noun mainly US and Canadian

1. a scandalmonger or gossip
2. another word for telltale (def. 1)

n.formed in English 1888 from tattle + tale. Probably patterned on telltale (1540s). A 16c. word for “tattle-tale” was pickthank.