This is the 2554th most frequent Japanese word.
失わ
"失わ" means "to lose."
Here, the word "失った" is used in the past tense to describe the loss of a tangible object.
大切な宝物を失った。
I lost my precious treasure.
In this example, "失い" refers to gradually losing an intangible concept such as trust.
彼は信頼を失い始めた。
He began to lose trust.
"失いそうだった" indicates a potential or imminent loss of an ability in a hypothetical context.