The standard inclusive definition of a Companion concerns someone who met the Prophet while believing in him and died as a Muslim. Lengthy association, prolific narration or military participation are not essential conditions; even a short meeting or a meeting in childhood can matter.
Meeting (liqāʾ) is broader than seeing with one’s eyes: a blind person may truly meet someone. Conversely, merely viewing a figure at a distance need not establish a qualifying meeting. The case of Ibn Umm Maktūm illustrates why the wording of the definition matters.
Companionship is established through credible reports, recognized transmission, historical indications and other reliable evidence. It is not established automatically through a shared name or an unsupported personal assertion.