De elegantiis terminorum

For it is said badly, cum oculis vidi I saw with my eyes, cum baculo percussit he struck with a stick.
Cum and tum respond to one another and almost always demand a verb of the indicative. And cum is joined to that which is lesser, tum to that which is greater. Therefore, because they seek a subject, as petrus cum doctus tum bonus est Peter is as learned as he is good. It is said badly: petrus cum doctus est tum ei studendum est.
Quintilian: Qua cum omnibus confitendum est, tum nobis praecipue qui rationem dicendi a bono viro non separamus Which is to be confessed by all, but especially by us who do not separate the reason of speaking from a good man—that is, by all much, but by me especially. Cicero on friendship: Cum saepe multa, tum nemini domi. The same: digna mihi res cum omni cognitione, tum nostra familiaritate visa est. But cum for "who" does not [take] the indicative, but the subjunctive, and not tum but tamen it requires after itself. Cicero: satis ne ostentare faciem videamur, cum praecipi nihil posse dicamus, tum aliis de rebus differere sileamus.
Cuncti all differs from quisque each, because it is joined to the positive and sometimes to the comparative, as cuncti boni all good men, cuncti meliores all better men. But quisque demands the superlative, as has been shown above, as optimus quisque each best man, not bonus quisque. Likewise cuncti are all, but joined and aggregated. Omnes all, however, even if they are in diverse places.
Curiosus curious/inquisitive is said from excessive and perverse care. Therefore, it is taken in a negative sense.
Curvum curved is said from the upper [side]; Convexum convex from the lower part.

The preposition 'de' compounded in a word sometimes increases it, as deprimo. Sometimes it deprives, as demens. Sometimes it is made downward, as descendo. It also is taken for "greatly," as deamo. It also is redundant, as demortuus. Sometimes it changes the meaning, as detineo.

Deitas deity is used by recent grammarians. By the most elegant, however, divinitas divinity is said.
Devenimus we arrive down from the higher to the lower. But on the contrary, pervenimus we arrive through/to to the higher, as pervenimus in montem, ad divinitas we arrive at the mountain, to divinity.
Debeo I ought often redundantly [is used] by the unskilled, as magister praecepit ut debeam studere—it is said ineptly; it must be said ut studeam that I may study.
Dedo to surrender is to give oneself to perpetuity and to the enemies. Hence dediticii surrendered persons, who, despairing, hand over themselves and their own to the enemies, or who, from fear of those higher and more powerful, commit themselves.
De facili easily is said ineptly, but facile.
Defectus defect/failure is placed badly for "fault," as when it is said defectu medicorum multi perierunt many have perished by the failure of doctors—[it should be] pro culpa medicorum for the fault of doctors. For he perishes by the failure (that is, lack) of doctors for whom a doctor is not present. Thus also it is said badly: Deus parcat tibi tuos defectus—but tuas culpas your faults must be said.
Demum at last/finally, when joined with is, ea, id or ita, it is made "only," as ea demum tibi cura est, ut mihi ita demum satisfacias that is the only care for you, that you satisfy me thus at last.