To be after something generally refers to trying to obtain, achieve or reach something, to pursue a particular objective, or wanting to talk or interact with someone. It can also be used in the context of a time connotation, meaning that one event is following after another in sequence.

a large tendon that runs from the heel to the calf

several small veins from the pericardium

a place for the burial of a corpse (especially beneath the ground and marked by a tombstone)

United States historian (1888-1965)

miss a step and fall or nearly fall

a form to use when sending a telegram

showy tropical tree or shrub native to Madagascar; widely planted in tropical regions for its immense racemes of scarlet and orange flowers; sometimes placed in genus Poinciana

a collection of Zoroastrian texts gathered during the 4th or 6th centuries

a watch during the night (as from midnight to 8 a.m.)