coincidental

形容词 coincidental:

1. occurring or operating at the same time
   同义词：coincident, coinciding, concurrent, co-occurrent, cooccurring, simultaneous

1. The similarity between these two essay is too great to be coincidental.
   这两篇文章雷同的地方很多，并非巧合所致。

co.in.ci.den.tal

adj.（形容词）
Occurring as or resulting from coincidence.
符合的：出现为或导致相符合的
Happening or existing at the same time.
同时发生的：发生在或存在于相同时间的

【引伸】
coin.ciden.tally
adv.（副词）