The cruciform dynamic absorber comprises two free–free beams that are mass loaded at their free ends and that are joined centrally at right angles at a point at which they are attached to the vibrating item or structure of concern. Both a lumped simple system and distributed mechanical systems such as beams and clamped circular plates are considered. The damping of the absorber beams and of the lumped and distributed mechanical systems is assumed throughout to be of the solid type. The branches (arms) of the cruciform dynamic absorber are generally tuned to the fundamental and second or third resonances of the distributed mechanical systems considered. Sometimes, one branch is tuned to the fundamental resonance of the distributed mechanical system concerned while the other branch, with essentially zero damping, is tuned off resonance, for example, to the frequency of a troublesome machinery discrete, thereby generating a pronounced trough in the transmissibility curve with a compensating transmissibility peak at a slightly higher frequency that is not necessarily of predominant magnitude.