Which term is right? "No load" or "infinite load"?
From an electrical perspective loading refers to what is impeding powerflow.

"weak pullup", refers to a high ohmage resistor. Likewise with generation and other such powersources a low load is one that requires low power flow &amp; this implies higher impedance.

Loading and impedance are inverse terms.  

Low load --> High resistance

High load --> Low resistance

Infinite load --> short circuit

No load --> infinite resistance