in place of, or as an alternative to
"Felix became a herpetologist instead"
"alternatively we could buy a used car"
in an alternative way
"Instead of taking the bus, you can alternatively walk to work if the weather is nice."
The word alternative comes from Latin and originally meant a choice between two options. Adding the suffix -ly, which turns adjectives into adverbs, created alternatively to describe doing something in another way or by means of an option.