The words lichen, liken sound the same but have different meanings and spellings. Why do lichen, liken sound the same even though they are completely different words?
The answer is simple: lichen, liken are homophones of the English language.
A composite organism made up of a fungus, usually an ascomycete, that grows symbiotically with an alga or a cyanobacterium and characteristically forms a crustlike or branching growth on rocks or tree trunks.
Any of various skin diseases characterized by patchy eruptions of small, firm papules.
To cover with lichens.
In <em>botany</em>, a plant or vegetable growth of the group <em>Lichenes</em>, ordinarily recognizable by its dry aspect and gray, brown, greenish, or blackish color, and its appearance in crusts, scaly patches, or bush-like forms on trees, rails, rocks, etc.
To see, mention, or show as similar; compare.
To make like; cause to resemble.
To represent, declare, or describe as like or similar; compare.
To allege, or think, to be like; to represent as like; to compare.
Definitions from The American Heritage® Dictionary of the English Language, 5th Edition., from The Century Dictionary., from the GNU version of the Collaborative International Dictionary of English. and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.
If they are spelled the same then they are also homographs (and homonyms); if they are spelled differently then they are also heterographs (literally "different writing").