a prescribed procedure to be followed routinely
"rote memorization has been the educator's standard operating procedure for centuries"
Something entirely soaked.
"He was so tired after his late-night sop that he couldn't even make coffee in the morning."
Initialism of sex on/over the phone.
give a conciliatory gift or bribe to
"He tried to sop his boss's anger by handing over an expensive watch after missing the deadline."
be or become thoroughly soaked or saturated with a liquid
"The heavy rain left the old wool coat completely sopping wet."
To steep or dip in any liquid.
"He used a cloth to sop up the spilled milk before it could ruin the carpet."
Initialism of State of Palestine.
"The news report clarified that SOP stands for the State of Palestine, distinguishing it from other regional abbreviations."