What is a Word Ladder?
A word ladder is a puzzle in which you transform one word into another by changing exactly one letter at each step. Every intermediate word must be a valid dictionary word. The puzzle was invented by Lewis Carroll in 1877.
The simple definition
A word ladder (also known as a doublet, word chain, word morph, word golf, or simply the change-one-letter game) is a word puzzle that links a start word to a target word through a sequence of intermediate words. Two adjacent words in the chain differ by exactly one letter, and every word in the chain — including the intermediates — must be a real word in the chosen dictionary.
The classic example is CAT to DOG:
CAT → COT → COG → DOG
Three steps. Each step changes one letter (T→T, then C→C, etc.). Every word along the way is in the dictionary. That is a valid word ladder.
The history: Lewis Carroll's Doublets
The word ladder was invented on Christmas Day 1877 by Lewis Carroll — Charles Lutwidge Dodgson, the mathematician and author of Alice's Adventures in Wonderland. Carroll had been visiting two young friends, the sisters Julia and Ethel Arnold, who complained of being bored, and he invented the puzzle on the spot to entertain them.
He called the puzzle Doublets. From 29 March 1879, Carroll's puzzles ran as a regular column in the British magazine Vanity Fair, and later that year they were collected into a small book, Doublets, A Word-Puzzle. Carroll set out three rules: the words at each end (the "doublets") must be linked by a chain of intermediate words; consecutive words must differ by one letter only; and only the letter in the same position may change. Those are still the rules of the modern word ladder.
Carroll's most famous example is transforming HEAD into TAIL:
HEAD → HEAL → TEAL → TELL → TALL → TAIL
Five steps. Carroll later set readers harder challenges, including APE to MAN, FLOUR to BREAD, and the famously tricky BLACK to WHITE.
The rules in plain English
- You start with two words of the same length: a start word and a target word.
- From the current word, change exactly one letter to make a new word.
- The new word must be a real word — one that appears in the agreed dictionary.
- You may not rearrange letters and you may not add or remove letters; the length stays fixed.
- Repeat the process until you reach the target word.
- The fewer steps in the chain, the better. The shortest possible chain is the optimal solution.
Worked examples
COLD to WARM
COLD → CORD → WORD → WARD → WARM
Four steps. Notice how we change letters one at a time, and how WARD is the bridge between WORD and WARM — only the first letter still differs from the target after WORD, then only the third, then only the last.
FLOUR to BREAD (Carroll's example)
FLOUR → FLOOR → FLOOD → BLOOD → BROOD → BROAD → BREAD
Six steps. The trick is the FLOOR ↔ FLOOD pivot — using the doubled O as a stepping stone.
APE to MAN (Carroll's example)
APE → APT → OPT → OAT → MAT → MAN
Five steps. Carroll appreciated the satirical edge of "evolving" APE into MAN one letter at a time, two years before The Origin of Species celebrated its 20th anniversary.
FISH to BIRD
FISH → FIST → GIST → GIRT → GIRD → BIRD
Five steps. GIRT and GIRD are unusual but valid English words — being a strong word-ladder player means knowing the corners of the dictionary.
Why some words are easy, others tricky
Some words have many one-letter neighbours: from CAT, you can reach BAT, EAT, HAT, MAT, OAT, PAT, RAT, SAT, VAT, COT, CUT, CAB, CAN, CAP, CAR, and CAW. Others, with rare consonants or unusual letter combinations, have very few. Words with lots of neighbours are easy stepping stones; words with few are the corners of the puzzle and often the trickiest bridges.
Why word ladders are surprisingly deep
The rules of a word ladder fit on a single line, but the puzzle is genuinely hard for a few reasons:
- Vocabulary breadth — finding intermediate words means recalling words you don't normally think of (CORD, GIRT, BROOD).
- Pathfinding — every move opens new options and closes others, so you have to plan with partial information and avoid dead ends.
- Pattern matching — recognising that TWO and TON are one letter apart, that HOME and HONE share three letters, etc., is a perceptual skill that grows with practice.
Word ladders also have an aesthetic appeal: a long, flowing transformation like FLOUR → BREAD or APE → MAN feels like watching one word slowly turn into another — a kind of slow-motion transmutation.
Word ladder vs other word puzzles
| Puzzle | Mechanic | Famous example |
|---|---|---|
| Word ladder | Change one letter at a time, all valid words | HEAD → TAIL |
| Wordle | Guess a hidden word from coloured clues | 5-letter daily |
| Anagram | Rearrange letters into a new word | LISTEN ↔ SILENT |
| Crossword | Fill a grid using clues | NYT crossword |
| Spelling Bee | Form words from a fixed set of letters | NYT Spelling Bee |
| Weaver | 4-letter daily word ladder | FOUR-letter only |
Word Labyrinth is the modern, mobile-first incarnation of Carroll's puzzle, with daily ranked ladders, an unlimited expert mode, leaderboards, streaks, and hints.
How Word Labyrinth fits in
Word Labyrinth is a free word-ladder game for the web, iOS and Android. The "labyrinth" name reflects the maze-like nature of the puzzle: from any word, many one-letter edits branch out, and finding the shortest path to the target feels like navigating a labyrinth. Each day there are 5 ranked puzzles of varying difficulty — short three-letter sprints, longer five- or six-letter ladders that need clever bridge words. There is also a leaderboard, a streak system, and an unlimited Expert mode for when the daily ladder is not enough.
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