Hi Mohit,
"A stakeholder is an individual, group, or organization who may affect, be affected by, or perceive itself to be affected by a decision, activity, or outcome of a project. Stakeholders may be actively involved in the project or have interests that may be positively or negatively affected by the performance or completion of the project. Different stakeholders may have competing expectations that might create conflicts within the project. Stakeholders may also exert influence over the project, its deliverables, and the project team in order to achieve a set of outcomes that satisfy strategic business objectives or other needs"
The above statement is from the PMBOK (page 30) and it goes on to explain who is a stakeholder and does he relate with the project.
Competitor is not stakeholder because he does not play any role in the success or failure of your project. He may not be even aware of your project. He is external to your project.
Best regards.