In an attemperate manner; with moderation, adjustment, or proper regulation.
From attemperate + -ly adverb suffix. This follows standard English adverbial formation rules but is extremely rare.
This adverb exists in English dictionaries but probably never appears in actual usage—it's an example of a word that's logically constructed but so awkward compared to simpler alternatives that writers avoided it.
Complete word intelligence in one call. Free tier — 50 lookups/day.