dFtdt
dFtdt is not a standard, widely defined term in physics or mathematics. In most reference contexts, the closest conventional symbol is dF/dt, the time derivative of force. If you encounter the string dFtdt, it is likely a typographical error or an idiosyncratic notation used by a particular author or software.
When interpreted as dF/dt, the quantity represents how the force acting on a body changes with time.
If dFtdt appears in a document, it is prudent to check the surrounding notation for context and
In summary, dFtdt is not a standard concept in itself; it is best treated as either a