A [[wp:semordnilap|semordnilap]] is a word (or phrase) that spells a different word (or phrase) backward.
"Semordnilap" is a word that itself is a semordnilap.

Example: ''lager'' and ''regal''
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;Task
Using only words from <u>[http://wiki.puzzlers.org/pub/wordlists/unixdict.txt this list]</u>, report the total number of unique semordnilap pairs, and print 5 examples. (Note that lager/regal and regal/lager should be counted as one unique pair.)
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;Related tasks
* [[Palindrome_detection|Palindrome detection]]
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