dead horse, but the word deceased is applied correctly only to human beings.
dead slow: A colloquialism for "lacking in spirit or liveliness, dull or tedious;" applied indiscriminately to persons or things.
deal: Used sometimes loosely for serve. Do not say "Deal the potatoes;" here serve is preferable.
debase. Compare demean.
decease should never be used as a verb.
deceive: Deception implies the production of a false impression. It is necessary, therefore, to distinguish between the accomplishment of this object and the bare attempt. Yet one frequently hears the expression "he is deceiving me," when it is clear that (as the attempt is unsuccessful) the idea intended to be conveyed is "he is attempting to deceive me."
decided, decisive: These terms are not exactly synonymous. A decided fact is one that is unmistakable and beyond dispute; a decisive fact is one that terminates a discussion. A decided victory is not necessarily a battle decisive of a campaign.
deduction is frequently confounded with induction. The in- mounts up from facts to law and is the process of inferring general conclusions from particular cases; the de- descends from law to facts and is that which is deduced from premises or principles. Induction is termed analysis; deduction, synthesis.