Competition

The act of seeking, or endeavoring to gain, what another is endeavoring to gain at the same time; common strife for the same objects; strife for superiority; emulous contest; rivalry, as for approbation, for a prize, or as where two or more persons are engaged in the same business and each seeking patronage; -- followed by for before the object sought, and with before the person or thing competed with.

The interaction between organisms or species for resources in an ecosystem

the act of competing as for profit or a prize; "the teams were in fierce contention for first place"

the contestant you hope to defeat; "he had respect for his rivals"; "he wanted to know what the competition was doing"