Dr. Johnson’s Dictionary

EA’GRE. n.s. [aeger, in Runick, is the ocean; in Islandick,
is to agitate, to incite.] A tide swelling above another tide,
observable in the river Severn.
For as an eagre rides in triumph o’er the tide,
The tyrant passions, hope and fear,
Did in extremes appear,
And flash’d upon the soul with equal force. Dryden.