firmly

The general adverb of firm, formed in Middle English as fermely from firm plus -ly. It is often paired with a softening adverb, as in corrected him firmly but gently or spoke firmly but kindly. In these pairs firmly carries the resolve and the second word keeps it from harshness. In comparisons, more firmly and most firmly are usual, though the inflected firmlier and firmliest also exist.

Here the adverb describes a hold rather than a tone: a rope tied to a post, or a man gripped firmly by the arm in Margery Allingham's The China Governess (1963). Grip is its natural partner, and firmly in its grip carries over to abstractions. The Economist in 2013 described dotcom mania holding higher education firmly in its grip. Unlike the sense of resolve, what matters here is whether something stays put.

A word of status rather than manner. It attaches to adjectives and participles that name a settled condition, such as firmly established, firmly rooted, or firmly illegal, and says how fixed that condition is, not how anything was done. Firmly illegal, said of slavery in England, shows that it fits even a legal standing. That makes it a natural choice whenever a question is presented as closed.