1. (

• quaver ,
• waver

) give off unsteady sounds, alternating in amplitude or frequency ;

2. (

• warble ,
• trill ,
• quaver

) sing or play with trills, alternating with the half note above or below ;

1. (

• quavering ,
• tremulous

) (of the voice) quivering as from weakness or fear; "the old lady's quavering voice"; "spoke timidly in a tremulous voice" ;