What is not a synonym for 'companion'?

• The word that is not a synonym for 'companion' is foe.

• Companion
English meaning: A person you spend a lot of time with often because you are friends or because you are travelling together:
Bangla Meaning: সঙ্গী; সহচর।
Example: The dog has been her constant companion these past ten years.

Friend:
English meaning: a person whom one knows and with whom one has a bond of mutual affection, typically exclusive of sexual or family relations.
Bangla Meaning: বন্ধু; বান্ধব; সখা; সুহৃদ; মিত্র; বয়স্য।
Example: She invited her friend to accompany her on the trip to the amusement park.

Foe:
English meaning: an enemy or opponent.
Bangla Meaning: (কাবিক্য) শত্রু।
Example: Despite being foes on the battlefield, they shared mutual respect for each other's skills.

Comrade:
English meaning: a companion who shares one's activities or is a fellow member of an organization.
Bangla Meaning: অন্তরঙ্গ সঙ্গী বা সহকর্মী; বিশ্বস্ত বন্ধু।
Example: The soldiers regarded each other as comrades, relying on one another for support during difficult missions.

Partner:
English meaning: a person who takes part in an undertaking with another or others, especially in a business or firm with shared risks and profits.
Bangla Meaning: অংশীদার
Example: They worked together as partners in their law firm, handling cases and clients collaboratively.

Source: Cambridge Dictionary