I'm writing up a manuscript and I use the term spectrogram quite a bit. I've defined a spectrogram as the magnitude squared of the short time Fourier transform of my signal. It's an estimator for a time-varying spectrum of a non-stationary process. I'd like to cite a paper for the origin of the term but I'm not sure what to cite. Could anyone give me some advice?
In Gabor's "Theory of Communication" (1947) these time-frequency plots are called "information diagrams" or "time/frequency diagrams". "Spectrogram" is another name for the diagram, not necessarily the signal; the wikipedia article says it is a "representation". Maybe time-varying spectrum would be a better term for the actual signal.
In any case, it would be better to reference the origin of the concept, rather than the origin of the word. The aforementioned paper may be a good one to start with. e.g. see Figure 1.6.
As many mentionned before, the term "Spectogram" refers to a representation of some data, with a similar etymology as the word "diagram".
The squared magnitude of the Fourier transform of a signal, short term or not, would be called a "Power Spectrum".
In fact, the power spectrum is defined as the Fourier transform of a signal multiplied by the complex conjugate of that Fourier transform. $$P(k)=F(x)\cdot F(x)^*=Re(F(x))^2+Im(F(x))^2$$ Where $P(k)$ is the power spectrum of your signal, with respect to the wavenumber $k$, and $F(x)$ denotes the Fourier transform of your signal ($x$ being your signal).
If your signal is purely symmetric, then there will be no imaginary part and the power spectrum would be equivalent to the squared magnitude of the Fourier transform.
You could then refer to your figures as "diagrams of the Power Spectrum", or do like me and refer to them as "Figure 1.5"!
I guess that some variations exist in different fields, as Wikipedia defines my mathematical construct as the "Energy Spectral Density" (http://en.wikipedia.org/wiki/Spectral_density) In a field where you work with actual physical density (mass/volume), we try to avoid using that word for anything else...