Final answer:
The prefix in the word 'UNDERESTIMATE' means 'below,' suggesting a judgement that is less than the actual worth or size.
Step-by-step explanation:
The meaning of the prefix in the word UNDERESTIMATE is 'below.' When combined with the stem 'estimate,' which means 'to judge the worth or size of,' the word underestimates signifies a judgement that falls short of the actual worth or size. In the broader context of prefixes, 'under-' typically conveys the idea of being less, beneath, or insufficient in some way.
By understanding the prefix 'under-,' one can get a better grasp of a range of words with this prefix, such as understand, underwear, and undermine, each reflecting a notion of 'below' or 'beneath' in some aspect.