The proper spelling of the phrase "ones darnedests" can be confusing due to the presence of three consecutive consonants in the middle. The correct spelling is "one's darnedest," with the addition of an apostrophe to indicate possession. The phonetic transcription of this phrase in IPA is /wʌnz ˈdɑːndɪst/. The "darn" sound is represented by the letter "d" followed by the letter combination "ar" pronounced as a single syllable. The suffix "-est" is pronounced as "ist."
The term "one's darnedests" is a variation of the phrase "one's damnedest", which means to do one’s utmost or to give maximum effort. The word "darnedest" is a euphemistic alteration of the word "damnedest", which is derived from the adjective "damned".
The word "damned" goes back to Middle English, where it originally meant "condemned" or "damned to eternal punishment". Its etymology can be traced to the Old English word "deman" (to judge) and the Proto-Germanic word "dōmaną" (to judge, assess, condemn). Over time, the term "damned" also took on the broader meaning of "used as a general intensifier", which is how it is used in the phrase "one's damnedest".