For a first order circuit the -3dB point is the so-called pole frequency and gives a phase shift of -45 deg.
For a second-order lowpass circuit, the phase shift at the pole frequency is -90 deg.
Hence, it makes sense to use the pole frequency for describing first and second order circuits.
...And, in addition, is the frequency at which asymptotes cut in Bode plots (cutoff frequency or corner frequency).
The term "cutoff" can be a bit misleading for some people, thinking erroneously that something abrupt happens at that frequency. Something rather abrupt happens at the "cutoff frequency" of waveguides, but it's the same term used for something totally different.