What does RSVP by COB mean?
RSVP by Close of Business.
RSVP is originally French (Répondez S'il Vous Plaît), and it means: please respond. If you are asking how to say RSVP in Spanish, there are quite a few ways. You can just say RSVP; it's understood almost everywhere. Or you could say: Se ruega contestación. Se ruega confirmación. Se ruega responder. Se ruega confirmar asistencia/presencia. Favor de confirmar su/tu asistencia/presencia. the list goes on.
RSVP is an abbreviation for the French phrase "Respondez S'il Vous Plait." In English, RSVP stands for "Reply Please!" Typically used in invitations when the hosts want to have a head count. Invitees who plan on coming must RSVP, those who are not planning on coming may RSVP, but a non-reply is assumed to be a "no".
Do you mean "spiders that make cobwebs"? Do you mean "poisonous" (like hemlock tea) or venomous (like cobra venom)? The word "cob" in "cobweb" just meant "spider." So a cobweb is just a spider web. Not all spiders are venomous. No spiders are known to be poisonous. Since black widows make webs, some "cob spiders" are highly venomous.