Crosswordese

Crosswordese is the group of words frequently found in US crossword puzzles but seldom found in everyday conversation. The words are usually short, three to five letters, with letter combinations which crossword constructors find useful in the creation of crossword puzzles, such as words that start or end with vowels (or both), abbreviations consisting entirely of consonants, unusual combinations of letters, and words consisting almost entirely of frequently used letters. Such words are needed in almost every puzzle to some extent. Too much crosswordese in a crossword puzzle is frowned upon by crossword-makers and crossword enthusiasts.
Knowing the language of "crosswordese" is helpful to constructors and solvers alike. According to Marc Romano, "to do well solving crosswords, you absolutely need to keep a running mental list of 'crosswordese', the set of recurring words that constructors reach for whenever they are heading for trouble in a particular section of the grid".
The popularity of individual words and names of crosswordese, and the way they are clued, changes over time. For instance, ITO was occasionally clued in the 1980s and 1990s in reference to dancer Michio Itō and actor Robert Ito, then boomed in the late 1990s and 2000s when judge Lance Ito was a household name, and has since fallen somewhat, and when it appears today, the clue typically references figure skater Midori Ito or uses the partial phrase "I to" (as in ["How was ___ know?"]).
When applicable, example clues will be denoted in square brackets and answers will be denoted in all caps, e.g. [Example clue] for ANSWER.
Portions of phrases are occasionally used as fill in the blank clues. For instance, "Et tu, Brute?" might appear in a puzzle's clue sheet as "_____, Brute?"
Many puzzles ask for the direction from one place to another. These directions always fall between the standard octaval compass points—i.e., North (N – 0° or 360°), Northeast (NE – 45°), East (E – 90°), etc.
The directions asked for on clue sheets are usually approximations. Starting at north and going clockwise, the directions are:
Because of crossword rules that restrict the usage of two-letter words, only entries of three or more letters have been listed.
Often these letters are clued as puns, e.g. the clue [Puzzle center?] for ZEES, referring to the two Zs in the center of the word "puzzle".
The "zed" spelling of Z is often indicated by a reference to a Commonwealth country, where that is the standard pronunciation (e.g. [British puzzle center?] for ZEDS).
Greek letters often appear as well, such as ETA.
Many puzzles ask for Roman numerals either as answers or as portions of answers. For instance:
Standard Roman numerals run from 1 to 3999, or I to MMMCMXCIX. The first ten Roman numerals are:
The following table shows the numerals used in crossword puzzles.
Postal abbreviations: Since the late 1970s, the post offices in the United States and Canada have used computerized letter sorting. This prompted the creation of the two-capital-letter abbreviations used today for all states and most provinces (i.e., "MN" for Minnesota and "QC" for Quebec). Previously, when mail was sorted by hand, many states and provinces had abbreviations of three to five letters. Many of these longer abbreviations are now part of crosswordese. (Notes: (1) Except for Texas, states with four- or five-letter names were generally spelled out. (2) Other states and provinces not shown below had the same two-letter abbreviations that are still used today.)
These once-common terms are especially rare or never found in new puzzles.