What is the opposite of embed? We often embed items from one space into another space, e.g. embedding plaintext items from $\{0, 1\}^m$ into some ring $R_q/\langle x^N + 1 \rangle$ for RingLWE.

What is the inverse of this action called? 

(Feel free to move this question to Math.SE or other related. Though I am specifically interested in the opposite of embed in the context of math and crypto, rather than the general English language.)
Embed usually implies the target algebraic structure is of larger cardinality (assuming finite). So, I would say project.