overexcitable

Etymology tree
Proto-Indo-European *úp
Proto-Indo-European *-er
Proto-Indo-European *upér
Proto-Germanic *uber
Old English ofer-
Middle English over-
English over-
English excite
Proto-Indo-European *-tḗr
Proto-Indo-European *-dʰlom
Proto-Indo-European *-dʰlis
Proto-Italic *-ðlis
Latin -bilis
Latin -ābilis
Old French -ablebor.
Middle English -able
English -able
English excitable
English overexcitable
From over- + excitable.