What is the meaning of Could?

simple past of can

conditional of can

1. Used as a past subjunctive (contrary to fact).

   Used as a past subjunctive (contrary to fact).

   Used to politely ask for permission to do something.

   Used to politely ask for someone else to do something.

   Used to show the possibility that something might happen.

   Used to suggest something.

   past participle of can

   Something that could happen, or could be the case, under different circumstances; a potentiality.

   Source: wiktionary.org