is similar to
having the power or quality of deciding
"the crucial experiment"; "cast the deciding vote"; "the determinative (or determinant) battle"
is similar to
having momentous consequences; of decisive importance
"that fateful meeting of the U.N. when...it declared war on North Korea"- Saturday Rev; "the fatal day of the election finally arrived"
is similar to
putting an end to all debate or action
"a peremptory decree"
see also
forming an end or termination; especially putting an end to doubt or question
"conclusive proof"; "the evidence is conclusive"
see also
of extreme importance; vital to the resolution of a crisis
"a crucial moment in his career"; "a crucial election"; "a crucial issue for women"