What's That Flat?

Altered state

A two-letter state abbreviation is replaced by another.

Alternade

A word or phrase is divided into two or more others by taking alternate letters in order.

Anagram

A word or phrase is turned into an appropriate comment or description when its letters are rearranged.

Beheadment

A word or phrase becomes another when its first letter is removed.

Bigram puzzles

Instead of single letters, bigrams (two-letter groups) are the basic units of these puzzles.

Change of heart

Two words or phrases are each divided into three pieces; then their middle pieces are switched to form two others.

Charade

A word or phrase is broken into two or more shorter ones.

Consonantcy

Two or more words or phrases share the same consonants in the same order.

Curtailment

A word or phrase becomes another when its last letter is removed.

Cyclegram

Each word in the base consists of two parts. The first part is identical to the second part of the preceding word; the second part is identical to the first part of the following word.

Deletion

A word or phrase becomes another when an interior letter is removed.

Double-Cross

Two words or phrases are each divided into two pieces; then their second pieces are switched to form two others.

Even exchange

Two words or phrases exchange all their letters in even positions to form two new words.

Head-to-Tail Shift

A word or phrase becomes another when its first letter is moved to its end.

Heart transplant

In a heart transplant, a letter or series of letters is taken from inside one word and transplanted to another.

Heteronym

Two words or phrases with the same spelling are used with different pronunciations and meanings.

Homoantonym

Two words or phrases sound like two other words or phrases that are antonyms.

Homonym

Two or more unrelated words or phrases are pronounced the same but spelled differently.

Interlock

Two or more words or phrases are interlocked to form a longer one.

Isomorph

All words have the same cryptogram pattern.

Italian-style

Has no cuewords. Instead, each stanza provides clues, more or less obliquely, to one solutions word or phrase.

Letter bank

One or more longer words or phrases are formed, each using all the letters in the bank at least once and as many more times as needed.

Letter change

A specified letter is changed to make a new word or phrase.

Letter Shift

A word or phrase becomes another when one letter is shifted to a new position.

Linkade

A word or phrase is broken into two or more shorter parts, which overlap by one letter.

Metathesis

A word or phrase becomes another when two letters are interchanged.

Mutual replacement

Two letters replace each other whenever they appear.

Order takeout

From a longer word, every sequence of two or more adjacent letters in consecutive alphabetical order is removed to form a shorter word.

Overloaded flats

Overloaded flats are puzzles in which a cueword can stand for any of two or more solution words.

Pasteover

A letter moves from its original position in a word and takes the place of another letter.

Phonetic

Puzzle variations in which sounds are the basic unit instead of letters.

Reversal

A word or phrase becomes another when reversed.

Spoonergram

A phrase becomes another when the initial consonant sounds in its component words (or stressed syllables) are swapped.

Terminal rotation

A pair of words becomes another pair of words when all four terminal letters shift position.

Transdeletion

A word or phrase becomes another when one letter is deleted and the others are transposed.

Transpogram

A word or phrase becomes another when divided into two parts, which are interchanged.

Transposal

A word or phrase becomes another when its letters are rearranged.