In mechanics, the dead center is the point at which an actual continuous movement stops. The dead spot on a plucked instrument is a fret on a fretboard whose sustain is significantly shorter than that of the neighboring frets. So it doesn't sound that long. With ukuleles in C6 tuning, this phenomenon is often found in the range of the F or F# tones.

It is due to the design; changing the string or the style of play does not help. Physical measurements suggest that where the string lies only relatively loosely (at the nut or fret), the vibrational energy of the string is transferred to the neck and leads to a damping of the overtones.