Final answer:
The word that matches 'zero' is 'null', which means the absence of value. Other options like 'bottom', 'nadir', and 'surplus' have different meanings.
Step-by-step explanation:
The word that matches 'zero' is null. This choice directly implies the absence of any amount or value, which is synonymous with zero. The other options do not accurately describe 'zero': 'bottom' generally refers to the lowest point or part of something, 'nadir' is the lowest point of a person's fortunes, and 'surplus' refers to an amount that is more than what is needed.
In terms of etymology, the word 'bottom' does not involve simple addition, assimilation, or twinning, making it unrelated to the concept of 'zero'.