Final answer:
The prefixes "sub-" and "infra-" both indicate a meaning of "under." Sub- is often used for things beneath others, while infra- signifies lower positions or structures. Knowledge of such prefixes is beneficial for vocabulary development.
Step-by-step explanation:
The meaning "under" can be represented by the prefixes "sub-" and "infra-." The prefix sub- is often used to indicate something that is beneath, below, or under something else. For example, "submarine" refers to a vessel that operates underwater. Similarly, the prefix infra- signifies a position beneath a structure or lower than a certain point, as in "infrared," which pertains to the part of the electromagnetic spectrum with wavelengths longer than those of visible light but shorter than those of microwaves, suggesting that these waves are "below" the spectrum of light visible to the human eye.
Understanding the use of prefixes such as sub- and infra- can help students decipher the meanings of complex words and enhance their vocabulary skills. This knowledge is particularly useful in subjects like medicine, where terms often describe the position of anatomical structures in relation to others, as well as in various academic disciplines.