Respectively means “in the order just mentioned.” It's a signal word that helps you match up two lists that correspond to each other.

If someone writes “Mars and Venus are the fourth and second planets from the Sun, respectively,” the word respectively tells you to pair them up in order: Mars (mentioned first) is the fourth planet, and Venus (mentioned second) is the second planet.

Here's another example: “The gold, silver, and bronze medals went to Chen, Rodriguez, and Johnson, respectively.” This means Chen got gold, Rodriguez got silver, and Johnson got bronze. The word creates a one-to-one match between the two lists in the same sequence.

Without respectively, you'd have to write something longer like “Chen won the gold medal, Rodriguez won the silver medal, and Johnson won the bronze medal.” The word respectively lets you say the same thing more efficiently.

You'll see this word often in textbooks, reports, and formal writing where authors need to present information clearly and precisely. It's especially useful in science and math, where keeping track of which number goes with which item really matters.