the state or quality of being sensitive; sensitiveness.

Physiology .

the ability of an organism or part of an organism to react to stimuli; irritability.

degree of susceptibility to stimulation.

Electricity .

the ability of a radio device to react to incoming signals, expressed as the minimum input signal required to produce a specified output signal with a given noise level.

the input, as voltage, current, or the like, required to produce full deflection in an electric measuring device, expressed as the ratio of the response to the magnitude of the input quantity.

noun

apathy , impassivity , insensitivity , numbness

noun

acuteness , affectibility , awareness , consciousness , delicacy , feeling , impressionability , nervousness , reactiveness , reactivity , receptiveness , sensation , sense , sensitiveness , subtlety , susceptibility , sympathy , sensibility , sentiment