start, initiate, begin, launch

start, initiation, beginning

checkbox (a window item, on the computer screen, which toggles check/uncheck by a single click)

governor

test results

the actual site where something occurs: (on) the ground, firsthand / practice

(television, electronics) fidelity, the accuracy of signal reproduction

a hostage / (archaic, original sense) indentureship, the state of being in servitude to another as collateral on or payment of a debt

to inject

injection