To decorate something is to add ornamentation to it or to embellish it in some way. To bedeck something is to go all out with your ornamental efforts, adorning that object (be it a tree, a room, or one’s outfit) to the point of gaudiness. (Why not? We’re all friends here!) Bedeck is not a very common term; the shorter verb deck, as in “We were all decked out for the party,” is more familiar. But when bedeck does make an appearance, it's likely for a special occasion. This glitzy verb might describe a person who is drenched in jewels, an architectural feature festooned with flowers, or a tree absolutely covered with ornaments.
The adjective immaculate describes things that are spotlessly clean or perfectly neat. It’s the adjective to reach for when clean simply isn’t enough. If you go to a friend’s house and their kitchen (inexplicably) has nary a dishtowel out of place nor speck of dust in view, it might qualify as immaculate. Immaculate is one of a handful of prefixed words in English that is better known than its unadorned counterpart: have you ever heard something described as maculate? The odds are no, but maculate is a perfectly fine and real adjective meaning “spotted; stained.”
To avoid something, like a dangerous or undesirable situation, is to keep clear of it or to prevent it from happening. The verb evade is a bit more cunning. To evade something is to get around it or to get out of it, usually by a degree of trickery or cleverness. This verb is most commonly used to talk about getting out of paying taxes, getting around legal consequences, or getting out of answering a question directly. This term’s earliest uses in English had to do with escaping literal pursuit or attack; while this specific sense has waned, the notion of escaping something undesirable remains a useful differentiator.