Under your breath

"Under your breath" means say something so quietly that no one else can hear exactly what you are saying. You can talk under your breath to let others know you are unhappy or angry with something but you don't want them to know what you are saying. For example he wanted me to watch a TV play,but I didn't like it.So I said under my breath"It's terrible." I wanted him to know I wasn't enjoying it,but he didn't know my exact feelings. Another example She said something under her breath,but I couldn't quite hear it.