vectorcardiogram

Etymology tree
Proto-Indo-European *weǵʰ-
Proto-Indo-European *wéǵʰeti
Proto-Italic *weɣō
Latin vehō
Proto-Indo-European *-tōr
Proto-Italic *-tōr
Latin -tor
Latin vectorlbor.
English vector
Proto-Indo-European *ḱerd-
Proto-Indo-European *ḱḗr
Proto-Indo-European *ḱr̥díyeh₂
Proto-Hellenic *kərdíyā
Ancient Greek καρδία (kardía)lbor.
English cardio-
Proto-Indo-European *gerbʰ-
Proto-Hellenic *grə́pʰō
Ancient Greek γρᾰ́φω (grắphō)
Proto-Indo-European *-mn̥
Ancient Greek -μᾰ (-mă)
Ancient Greek γράμμα (grámma)lbor.
English -gram
English cardiogram
English vectorcardiogram
From vector + cardiogram.