Strengthen, v. t. [imp. & p. p. Strengthened; p. pr. & vb. n. Strengthening.]
1. To make strong or stronger; to add strength to; as, to strengthen a limb, a bridge, an army; to strengthen an obligation; to strengthen authority. Let noble Warwick, Cobham, and the rest, . . . With powerful policy strengthen themselves. Shak.
2. To animate; to encourage; to fix in resolution. Charge Joshua, and encourage him, and strengthen him. Deut. iii. 28.
Syn. -- To invigorate; confirm; establish; fortify; animate; encourage.
1 other Webster entry under this spelling
Strengthen, v. i.
To grow strong or stronger. The young disease, that must subdue at length, Grows with his growth, and strengthens with his strength. Pope.
Shades of meaning
Fernald has no entry of its own for strengthen; he lists it under confirm.
He lists it without comment; the entries above explain its neighbors.