Both these adjectives are more formal synonyms for “nonstop.” Constant, the more frequent word, describes something that continues without stopping or pausing: under constant pressure. In this sense, constant often (though not always) has a negative connotation—and unremitting more so, as it suggests never even letting up or abating, let alone ceasing. The nouns that appear most commonly with unremitting are pain, effort, stress, hostility, bleakness, and pressure, and the verbs, endure and withstand. However, unremitting is sometimes used to describe an admirable and faithful effort, and can even, through contrast with its usual associations, evoke a powerful good: unremitting kindness.
Stuff has over a dozen dictionary definitions for the noun form alone. The sense of “personal belongings” (all his stuff) is the focus here. If the stuff in question is composed of things used for a particular purpose (drug paraphernalia; sewing paraphernalia), or of memorabilia and other themed items (Grateful Dead paraphernalia), paraphernalia is a strong synonym. But there is another, much less common sense of paraphernalia that means “personal belongings.” Historically, paraphernalia was women’s stuff: as a legal term it meant things a woman owned that were not included in her dowry and therefore not her husband’s property—usually clothing and personal items. So paraphernalia could be an interesting synonym for stuff (a purse jammed with her paraphernalia) if its predominant association with illegal drug use doesn’t interfere with the intended meaning.
There’s no consensus on what ingredients belong in ambrosia salad, the traditional Thanksgiving treat—or on whether it actually is a treat—but we’re certain that the word ambrosia comes from a Greek word for the food (or drink or anointing oil) of the gods, which was believed to confer immortality. The English adjective, ambrosial, describes something unusually delicious or fragrant—heavenly, you could say. Ambrosial food, wine, nectar, tea, and scent are some of its most frequent uses. With the adjective ambrosial, you can turn a cocktail into an elixir of youth.