Free The Blue Book of Grammar and Punctuation by Jane Straus, Lester Kaufman, Tom Stern Page B

we say, “Good old Joe is here,” we refer to Joe. If we say, “That man with the ready laugh is here,” we allude to Joe, but we never mention his name.
    Allude is also sometimes confused with elude , which means “to escape” or “avoid capture.”
    ALLUSION, ILLUSION
    Allusion , the noun form of allude , is an indirect, sometimes sly, way of talking about something or someone.
    An illusion is a false perception.
    ALLOWED, ALOUD
    Allowed : permitted.
    Aloud : said out loud.
    ALTAR, ALTER
    Altar : a pedestal, usually religious.
    Alter : to modify; to change.
    AMBIGUOUS, AMBIVALENT
    Something is ambiguous if it is unclear or has more than one meaning.
    Ambivalent describes a mixed or undecided state of mind: Her ambiguous remark left him feeling ambivalent about her .
    AMIABLE, AMICABLE
    Both words mean “friendly,” but amiable generally describes a pleasant person; amicable generally describes a cordial situation: The amiable couple had an amicable divorce .
    AMID, AMIDST
    Either is acceptable, but many writers prefer the more concise amid .
    AMOUNT, NUMBER
    Use amount for things that cannot be counted and number for things that can be counted: This amount of water is enough to fill a number of bottles .
    The culprit is amount . Some might incorrectly say “a large amount of bottles,” but no one would say “a large number of water.”
    a.m., p.m .
    The abbreviation a.m . refers to the hours from midnight to noon, and p.m . refers to the hours from noon to midnight. Careful writers avoid such redundancies as three a.m. in the morning (delete in the morning ) or eight p.m. this evening (make it eight o'clock this evening ).
    To avoid confusion, use midnight instead of twelve a.m . and noon instead of twelve p.m .
    The terms also are frequently written as a.m., p.m.; am , pm; and am, pm .
    AN
    See a, an .
    AND/OR
    â€œObjectionable to many, who regard it as a legalism,” says Roy H. Copperud in A Dictionary of Usage and Style . Either say and or say or .
    ANECDOTE, ANTIDOTE
    An anecdote is a brief, amusing tale.
    An antidote counteracts or reduces the effects of something unpleasant or even lethal. There are antidotes for snakebites, but there is no known antidote for boring anecdotes.
    AN HISTORIC
    Some speakers and writers use an with certain words starting with an audible h —the word historic heads the list. But why do those who say an historic occasion say a hotel, a hospital, a happy home ? There is no valid reason to ever say an historic, an heroic, an horrific , etc., and anyone who does so is flirting with pomposity.
    ANXIOUS, EAGER
    In casual usage, anxious has become a synonym for eager , but the words are different. Whereas eager means “excited” or “enthusiastic,” anxious , like anxiety , denotes uneasiness.
    ANY MORE, ANYMORE
    Use the two-word form to mean “any additional”: I don't need any more help .
    Use anymore to mean “any longer”: I don't need help anymore .
    ANY TIME, ANYTIME
    Traditionalists do not accept the one-word form, anytime . But it is everywhere, and there's no turning back.
    There does seem to be a difference between You may call anytime and Do you have any time? Always use the two-word form with a preposition: You may call at any time .
    APPRAISE, APPRISE
    A school district official was quoted as saying, “We have been appraised of all the relevant issues.” Bad choice. The word appraise means “to decide the value of.” The gentleman clearly meant apprised , which means “informed.”
    ASCENT, ASSENT
    Ascent : a climb; movement upward.
    Assent : an agreement (noun); to agree (verb).
    AS REGARDS
    See in regard(s) to, with regard(s) to .
    ASSUME, PRESUME
    Assume : to take for granted without evidence.
    Presume : to believe based on evidence.
    ASSURE, ENSURE, INSURE
    To assure is to promise or say with confidence. It is more about saying than doing: I assure you that