Happy New Year/Happy new year, and other holidays, too.

“New Year’s Eve” and “New Year’s Day” always start with capital letters and always take an apostrophe. When you’re wishing someone “Happy New Year,” most sources say that ‘New Year’ should be capitalized, too.

But dictionaries give conflicting advice on whether to capitalize the singular ‘New Year.’ “Webster’s New World College Dictionary” lower-cases it. So technically, you could write “Happy new year.” But “Merriam-Webster’s” and “American Heritage” dictionaries both capitalize it: New Year.

If you’re talking in generic terms, you can use the plain-old noun “year” and modify it with the plain-old adjective “new” to get lowercase “new year.” This is especially common with “the”: “We will see many changes in the new year.”

The third Monday in January is Martin Luther King Jr. Day, which the “Associated Press Stylebook” and the “Chicago Manual of Style” list without a “Rev.” without a “Dr.” and without any commas setting off “Jr.”

Valentine’s Day always has an apostrophe and is always capitalized. Look this name up in “Webster’s New World” and you’ll see the definition is “Saint Valentine’s Day,” but look it up in “Merriam-Webster’s” and you’ll see “St. Valentine’s Day.” You can use any of these to refer to the holiday on which you give a valentine to your valentine. That’s because the noun forms that mean your sweetheart or a greeting card are both lowercase.

If only Presidents Day were as easy. The dictionaries say this holiday, celebrated the third Monday in February, is plural possessive: Presidents’ Day. But AP says it’s the apostrophe-less Presidents Day, in which the first word is functioning as an adjective and therefore is not possessive.

Interestingly, Presidents Day isn’t a federal holiday. Though certain departments of the federal government, as well as some state and local governments, call it Presidents’ Day, the official name is actually Washington’s Birthday — even though it’s meant to celebrate Lincoln’s Birthday and to honor all other presidents as well.

St. Patrick’s Day never refers to more than one Patrick, so it’s always singular possessive. April Fools’ Day is the unanimous choice of my dictionaries and AP, though the Chicago manual refers only to All Fools’ Day. And the Fourth of July can be written like this or as the 4th of July or even July Fourth.

Memorial Day is obvious, but Veterans Day isn’t. The style guides and dictionaries I checked agree that this Nov. 11 celebration once called Armistice Day takes no apostrophe. Usage guides, however, note that Veterans’ Day is also a popular choice.

Resource: June Casagrande