One can never tell can they?
A lever or projecting part on a machine that intermittently makes contact with a cam or other part so as to give or receive motion.
A lever or projecting arm that moves or is moved by contact with another part, usually to transmit motion, as between a driving mechanism and a valve.
A sliding rod, intermittently struck by a cam, for moving another part, as a valve.
Zetecs use parts that are definitely flat and tappets. Maybe not lifter, since lifter lifts up and these push down. Irrelevant however since the intended action is the exact same, to open the valve.
I guess we could call them....openers?