Building in silos is when you get something done by yourself or with your direct teammates. Cross team collaboration involves e.g. a weekly sync, coauthored design documents, code changes made in modules you’ve never seen before reviewed by people you don’t know, tasks that are critical blocking dependencies for you but totally irrelevant to the decision-makers of the teams that need to allocate time for them. The extent to which a company is siloed is the extent to which its engineers are talking to their desk neighbors and getting things done vs. navigating communication overhead and being blocked on people quite remote from them and their goals.

It’s hard to believe you could have a nimble and cohesive team at the scale of a large corporation, because the number of communication edges gets silly. Dunbar’s number and all that. You can have team nimble and cohesive teams within large corporations. But having several distinct networks is otherwise known as being siloed.