# Is there a symbol for “Time Displacement”

Does the "Time Displacement" property of a wave function have an associated symbol?

Amplitude = $\hat U$

Period = $T$

Ordinary frequency = $f$

Angular frequency = $ω$

Phase = $ϕ$

Time Displacement = ?

The term appears in my college lecture notes:

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Is this even a mathematical term? – tomasz Oct 21 '12 at 9:24
$\mathrm d t$? $\Delta t$? – FrenzY DT. Oct 21 '12 at 9:26
@tomasz I am asking because it appears in my college notes, so maybe - maybe not. It is calculated ϕ/ω so might just be my lecturer's weird way of saying phase shift – jsj Oct 21 '12 at 9:28
I would use $t_1$ – Elements in Space Jan 5 '13 at 16:57

For this analogy assume $\alpha > 0$.
The author of that text is simply using the term time displacement to mean the time it would take the lagging function to achieve the same $y$ value (displacement, field magnitude etc.) as the leading function.
In that sense $\Delta t$ is not a bad choice for a symbol. Especially considering that distance displacement is commonly represented by the symbol $\Delta x$.
Physicists use $t$ for time, the variable, units second.