Moving or happening freely, with nothing in the way to slow it down or stop it. It is used about movement and about processes: unimpeded access to a building, unimpeded traffic, an unimpeded view of the sea, aid reaching a city unimpeded, growth continuing unimpeded. Two things are worth noticing. First, the word implies that something COULD have blocked it — a wall, a rule, an official, a crowd — and did not. That is why "unimpeded access" is such a common phrase in law and news: someone had the power to refuse and didn't. Second, it works both as a describing word before a noun (unimpeded progress) and as a word after the verb telling you how something went (the water flowed unimpeded). It is formal; in daily speech people say "with no problem" or "nothing was in the way".