(~s)
1.
A ~ is something that increases a positive or desirable quality.
It was amazing what a morale ~ her visits proved...
Praise is a great confidence ~.
N-COUNT: usu n N
2.
A ~ is an extra engine in a machine such as a space rocket, which provides an extra amount of power at certain times.
Ground controllers will then fire the ~, sending the satellite into its proper orbit.
N-COUNT
3.
A ~ is a small injection of a drug that you have some time after a larger injection, in order to make sure that the first injection will remain effective.
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4.
A ~ is someone who supports a sports team, organization, person, or place very enthusiastically. (AM)
A former associate of Mr. Pierce’s was among the project’s ~s.
= supporter
N-COUNT: oft supp N, N n