Chancing upon is a phrase that refers to discovering or stumbling upon something unexpectedly. The opposite of chancing upon can be premeditatedly finding something, seeking something out intentionally, or deliberately looking for something. The antonyms of chancing upon include carefully planning, deliberately searching, consciously seeking, and purposefully finding. While chancing upon something can be considered fortunate, actively seeking and finding something can be a result of hard work, dedication, and perseverance. Therefore, the opposite of chancing upon can also be interpreted as achieving something through conscious effort and determination.