Pronunciation: [at wˈɒn mˈɜːsi] (IPA) 
The spelling of "at one mercy" can be confusing due to the pronunciation of the word. It is pronounced as /ət wʌn ˈmərsi/ and means "under someone's mercy or control." The word "at" is pronounced as /ət/, similar to the short "u" sound in "cup." "One" is pronounced as /wʌn/, with a short "u" sound as well. "Mercy" is pronounced as /ˈmərsi/, with the stress on the first syllable and the short "e" sound in "bet."
The phrase "at one's mercy" implies being completely vulnerable or submissive to someone else's control or power, without any ability to protect oneself or escape. When a person is "at one's mercy," they are entirely subjected to the will and whims of another individual.
The term "mercy" refers to a sense of kindness, compassion, or leniency that is shown toward someone who is in a vulnerable or disadvantaged position. In this context, "at one's mercy" highlights the power dynamic in which one person holds complete authority over another, leaving the latter helpless and unable to resist or defend oneself.
This expression is often used metaphorically to describe situations where someone is entirely reliant on the benevolence or goodwill of another person. It can imply being completely defenseless, as if the person in power has the ability to dictate the outcome of a situation without opposition or consequence. Additionally, it suggests that the person in control has the option to exercise their authority in either a benevolent or malevolent manner, and the person "at their mercy" has no say or influence in the matter.
Overall, being "at one's mercy" entails being in a position of extreme vulnerability and dependence, where one's fate or well-being is entirely in the hands of another individual.
