An alphamegalog is an alphabetical list of items, selected from a specified superset, as being the greatest member of the superset for each letter of the alphabet.  Here are some example alphamegalogs.

An alphamegalog has the following characteristics:

1. The list contains one item for each letter that has at least one corresponding member in the superset. Thus, the number of items in the alphamegalog is equal to or less than the number of letters in the alphabet. 
2. Each member of the superset is identified by a word, phrase, name, title, or term. This word, phrase, name, title, or term is the member’s “alphabetical representation,” abbreviated ‘alpharep.’
3. Every alphamegalog has a definition that explicitly or implicitly defines each of the following particulars:
   • The superset. Any restrictions must be identified, but for some cases there are implied assumptions about certain restrictions. For instance, if not explicitly specified, the alphamegalog of cities in a region implicitly assumes that ‘cities’ include various other forms of locality, such as towns, villages, census designated places, and postal designated places. 
   • The correspondence between the superset members and the alphabet. If not explicitly specified, the implied assumption for this correspondence is the first letter of the alpharep. 
   • Any restrictions on how each member’s alpharep is determined. Many things have official or formal alphareps, but informal alphareps such as nicknames can also be allowed by the alphamegalog’s definition. Some definitions allow an informal alpharep for a given letter only when no member of the superset has a formal alpharep for that letter, and only if that member is not already in the alphamegalog based on its formal alpharep. For instance, in the alphamegalog of the elements in the earth by total mass, since there is no element with a formal alpharep beginning with Q, quicksilver can be used for mercury, since mercury is not the M element. 
   • The measure of greatness. There cannot be an implicit assumption for the general case, but there are implicit assumptions for particular categories. For instance, if not explicitly specified, the alphamegalog of cities in a region implicitly assumes that the measure of greatness is the population within the city proper.
4. Creator’s License: The creator of an alphamegalog has a “license” to bend the rules as he pleases. Although alphamegalogs can be strict about adhering to objective rules, part of the fun in creating alphamegalogs is to get creative and mix in some unexpected elements to add spice.
   • Subjectivity versus objectivity. An alphamegalog may be wholly objective or subjective, or a combination of both. The measure of greatness may be objective facts that can be proven. On the other hand, greatness may be the personal preferences of the creator; for example, a city alphamegalog could be based entirely on the creator’s favorite cities in a given region. A city alphamegalog may be primarily objective, but if two cities are fairly close in population, the creator may choose the smaller one for his own reasons. Similarly, when it is hard to determine objectively which member of the superset belongs in the alphamegalog, the creator may choose an alternative measure of greatness for a particular letter. When there appears to be no member in the superset for a given letter, the creator may choose whether to leave that letter blank or come up with an interesting, clever, or cute “phony” item.