It seems like you might be referring to a "triad" in music theory, where the third note of the chord is placed at the bottom (inverted). In a standard triad, the notes are typically arranged in a specific order (root, third, fifth). When you invert the triad so that the third is the lowest note, it’s called a "first inversion."
For example, in a C major triad (C, E, G), the first inversion would have E as the lowest note, resulting in the order E, G, C. If you have a specific context (like a song or a musical piece) in mind, feel free to provide more details!