Antonyms of adj excitable

2 senses of excitable

Sense 1
excitable (vs. unexcitable) -- (easily excited)

unexcitable (vs. excitable) -- (not easily excited; "an unexcitable temperament")
        => steady -- (not easily excited or upset; "steady nerves")

Sense 2
excitable, irritable -- (capable of responding to stimuli)

INDIRECT (VIA sensitive) -> insensitive -- (not responsive to physical stimuli; "insensitive to radiation")

Similarity of adj excitable

2 senses of excitable

Sense 1
excitable (vs. unexcitable) -- (easily excited)
       => high-keyed -- ((of persons) excitable)
       => quick, warm -- (easily aroused or excited; "a quick temper"; "a warm temper")
       => skittish, flighty, spooky, nervous -- (unpredictably excitable (especially of horses))

Sense 2
excitable, irritable -- (capable of responding to stimuli)
       => sensitive (vs. insensitive) -- (responsive to physical stimuli; "a mimosa's leaves are sensitive to touch"; "a sensitive voltmeter"; "sensitive skin"; "sensitive to light")