What is the meaning of Overtone?

A tone whose frequency is an integer multiple of another; a member of the harmonic series.

An implicit message (in a film, book, verbal discussion, or similar) perceived as overwhelming the explicit message.

An implicit message (in a film, book, verbal discussion, or similar) perceived subtly alongside, but not overwhelming, the explicit message.

To give an overtone to.

Source: wiktionary.org