Treat, v. t. [imp. & p. p. Treated; p. pr. & vb. n. Treating.]
Etymology: [OE. treten, OF. traitier, F. traiter, from L. tractare to draw violently, to handle, manage, treat, v. intens. from trahere, tractum, to draw. See Trace, v. t., and cf. Entreat, Retreat, Trait.]
1. To handle; to manage; to use; to bear one's self toward; as, to treat prisoners cruelly; to treat children kindly.
2. To discourse on; to handle in a particular manner, in writing or speaking; as, to treat a subject diffusely.
3. To entertain with food or drink, especially the latter, as a compliment, or as an expression of friendship or regard; as, to treat the whole company.
4. To negotiate; to settle; to make terms for. [Obs.] To treat the peace, a hundred senators Shall be commissioned. Dryden.
4 more senses
5. (Med.)
To care for medicinally or surgically; to manage in the use of remedies or appliances; as, to treat a disease, a wound, or a patient.
6. To subject to some action; to apply something to; as, to treat a substance with sulphuric acid. Ure.
7. To entreat; to beseech. [Obs.] Ld. Berners.
2 other Webster entries under this spelling
Treat, v. i.
1. To discourse; to handle a subject in writing or speaking; to make discussion; -- usually with of; as, Cicero treats of old age and of duties. And, shortly of this story for to treat. Chaucer. Now of love they treat. Milton.
2. To negotiate; to come to terms of accommodation; -- often followed by with; as, envoys were appointed to treat with France. Inform us, will the emperor treat! Swift.
3. To give a gratuitous entertainment, esp. of food or drink, as a compliment.
Treat, n.
1. A parley; a conference. [Obs.] Bid him battle without further treat. Spenser.
2. An entertainment given as an expression of regard.
3. That which affords entertainment; a gratification; a satisfaction; as, the concert was a rich treat.
Shades of meaning
Fernald has no entry of its own for treat; he lists it under transact.
Where he writes about it:
To negotiate and to treat are likewise collective acts, but both these words lay stress upon deliberation with adjustment of mutual claims and interests; transact, while it may depend upon previous deliberation, states execution only. — from transact
Negotiate has more reference to execution than treat; nations may treat of peace without result, but when a treaty is negotiated, peace is secured; the citizens of the two nations are then free to transact business with one another. — from transact