Hijacking this page to insert a glossary of terms / FAQ, because I don't have a strong electronic background to understand every single term out there.
There seems to be a distinction between asserting a signal and driving a signal, as seen in the MachXO2 datasheet:
The MachXO2 asserts INITN active low, and drives DONE low. When INITN and DONE are asserted low the device moves to the initialization state.
According to Electronics SO, asserting a pin is to set it to its active state, which in turn depends on whether a pin is active-high or active-low. A pin marked $$ \text{RESET} $$ is active-high and $$ \overline{\text{RESET}} $$ is active low.
A more precise definition involves making a transition from inactive to active when asserting a pin (e.g. when already active, the pin must be first set inactive then active again).
De-asserting a pin/signal can mean one of two things: