In English, are there any words which encrypt to other words under the Caesar Cipher? Are there any words in the English language which, when encrypted using the Caesar Cipher with any key, result in another English word? How may one go about determining which Caesar shifts are weakest in this context?
Actually, we have a four-way (that is, four words that will can be converted into any of the others with the right shift).  These words are:

ax, by, he, if


Other two letter words are:

am &lt;-&gt; my
at &lt;-&gt; pi
do &lt;-&gt; it
hi &lt;-&gt; no


We also have

the &lt;-&gt; max


I didn't do a systematic search for words over two letters; there certainly do appear that they are moderately plentiful



I've done a more systematic search over longer words; ignoring extremely obscure words, the best I found were

abjurer &lt;-&gt; nowhere
inkier &lt;-&gt; purply
fusion &lt;-&gt; layout
manful &lt;-&gt; thumbs
primero &lt;-&gt; sulphur
steeds &lt;-&gt; tuffet


(OK, 'tuffet' missed by 'obscure' criteria; I still liked it).

So, yes, there certainly are words can be be encoded into other words