trembler

Trembler is a term with several senses across technology, biology, and everyday language. In electronics and telecommunications, a trembler is an electromechanical device that rapidly opens and closes a circuit, producing a buzzing or pulsing output. Common forms include the trembler relay and related buzzers, used in early telephone equipment, intercoms, doorbells, and as vibration-based power converters in some mid-20th-century car radios.

In ornithology, trembler is the common name given to several small passerine birds, typically insectivorous, found in tropical regions. These species are often shy and skulking, with quick, tremor-like vocalizations that inspired their name. The term appears in common names such as tremblers and trembler babblers, covering multiple species across different genera.

In everyday usage, trembler can refer to a person who trembles or is easily frightened, or more generally to someone who is nervous or jittery. The word derives from tremble and is used in figurative expressions describing timidity or anxiety.