The usual term given to a word which, when spelled backwards, has a different meaning is "semordnilap" (palindromes backwards).
Examples of semordnilap are:
- Desserts / Stressed
- Stink / Knits
- Evil / Live
- Regal / Lager
- Raw / War
- Smart / Trams
- Devil / Lived
- God / Dog
- Straw / Warts
- Time / Emit
Interestingly, some semordnilaps are purpose made. The term 'yob' was supposedly made as a semordnilap of 'boy' - very apt :-)
Palindrome is the term given to words or phrases which read the same forwards or backwards for example:
- Noon
- Navy Van
- Amore Roma
- No 'x' in Nixon
- As I pee sir, I see Pisa
The longest single word palindrome in English is Redivider. However, in Finnish there is a 25 letter Palindrome which is SAIPPUAKUPPINIPPUKAUPPIAS and apparently means 'soap cup trader'
Is it just me or was something lost in translation there? Lol