Too, adv.
Etymology: [The same word as to, prep. See To.]
1. Over; more than enough; -- noting excess; as, a thing is too long, too short, or too wide; too high; too many; too much. His will, too strong to bend, too proud to learn. Cowley.
2. Likewise; also; in addition. An honest courtier, yet a patriot too. Pope. Let those eyes that view The daring crime, behold the vengeance too. Pope. Too too, a duplication used to signify great excess. O that this too too solid flesh would melt. Shak. Such is not Charles his too too active age. Dryden.
Syn. -- Also; likewise. See Also.
Shades of meaning
Fernald has no entry of its own for too; he lists it under also.
Where he writes about it:
The words fall into two groups; as well as, besides, in addition, too, withal, simply add a fact or thought; also (all so), in like manner, likewise, similarly, affirm that what is added is like that to which it is added. — from also