Double-crosser and Tipster

Double-crosser noun - One who betrays a trust or an allegiance.

Tipster and double-crosser are semantically related In some cases you can use "Tipster" instead a noun phrase "Double-crosser".

Tipster noun - One who sells advice about gambling or speculation (especially at the racetrack).

Double-crosser and tipster are semantically related in sneak topic. Sometimes you can use "Double-crosser" instead a noun "Tipster", if it concerns topics such as informer, reporter, informer to police.