Definition of on/upon impact
: at the time of hitting something The bomb exploded on/upon impact (with the ground).
Word by Word Definitions
: on the surface : on it
: thereafter, thereon
: to fix firmly by or as if by packing or wedging
: to press together
: to have a direct effect or impact on : impinge on
: an impinging or striking especially of one body against another
: a forceful contact or onset
: the impetus communicated in or as if in such a contact
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