The Reverse(s) command returns a string formed by reversing the characters in string s.

All of the StringTools package commands treat strings as (null-terminated) sequences of $8$-bit (ASCII) characters.  Thus, there is no support for multibyte character encodings, such as unicode encodings.

$\mathrm{with}\left(\mathrm{StringTools}\right)\:$

$\mathrm{Reverse}\left(''drawer''\right)$

$''reward''$

$\mathrm{Reverse}\left(''cat''\right)$

$''tac''$

$\mathrm{Reverse}\left(\mathrm{Reverse}\left(''cat''\right)\right)$

$''cat''$

$\mathrm{WordList}≔''/usr/dict/words''\:$

$\mathrm{WordList}≔\mathrm{FileTools}:-\mathrm{JoinPath}\left(\left[\mathrm{kernelopts}\left(':-\mathrm{datadir}'\right)\,''help''\,''StringTools''\,''words.dat''\right]\right)\:$

$\mathrm{words}≔\mathrm{remove}\left(\mathrm{type}\,\left\{\mathrm{op}\right\}\left(\mathrm{Split}\left(\mathrm{readbytes}\left(\mathrm{WordList}\,\mathrm{\infty }\,'\mathrm{TEXT}'\right)\,''\backslash n''\right)\right)\,\left\{''''\,'\mathrm{character}'\right\}\right)\:$

$\mathrm{RW}≔\mathrm{sort}\left(\left[\mathrm{op}\right]\left(\mathrm{remove}\left(\mathrm{IsPalindrome}\,\mathrm{words}\mathbf{intersect}\mathrm{map}\left(\mathrm{Reverse}\,\mathrm{words}\right)\right)\right)\right)$

$\mathrm{RW}≔\left[''AC''\,''CA''\,''IR''\,''MN''\,''NM''\,''RI''\,''TV''\,''VT''\,''abut''\,''ah''\,''am''\,''are''\,''as''\,''ate''\,''avid''\,''bad''\,''bag''\,''ban''\,''bard''\,''bat''\,''bin''\,''bird''\,''bog''\,''bon''\,''brag''\,''bud''\,''burg''\,''bus''\,''but''\,''cit''\,''dab''\,''dam''\,''deep''\,''deer''\,''dew''\,''dial''\,''dim''\,''diva''\,''dog''\,''don''\,''doom''\,''door''\,''drab''\,''draw''\,''drib''\,''dual''\,''dub''\,''edit''\,''eel''\,''eh''\,''em''\,''emit''\,''en''\,''enol''\,''era''\,''eta''\,''even''\,''evil''\,''flog''\,''flow''\,''gab''\,''gal''\,''gar''\,''garb''\,''gas''\,''gel''\,''gnat''\,''gob''\,''god''\,''golf''\,''got''\,''grub''\,''gulp''\,''gum''\,''gut''\,''ha''\,''haw''\,''hay''\,''he''\,''ho''\,''hoop''\,''it''\,''iv''\,''ix''\,''jar''\,''keel''\,''keep''\,''knot''\,''lag''\,''lager''\,''laid''\,''lap''\,''laud''\,''lee''\,''leek''\,''leer''\,''leg''\,''leper''\,''lever''\,''liar''\,''lit''\,''live''\,''lone''\,''loop''\,''loot''\,''lop''\,''ma''\,''mad''\,''mar''\,''mart''\,''mat''\,''may''\,''me''\,''meet''\,''mid''\,''mood''\,''moor''\,''mug''\,''nab''\,''nap''\,''ne''\,''net''\,''neve''\,''nib''\,''nip''\,''nit''\,''no''\,''nob''\,''nod''\,''not''\,''now''\,''nut''\,''oat''\,''oh''\,''on''\,''pal''\,''pan''\,''par''\,''part''\,''pat''\,''pay''\,''peed''\,''peek''\,''per''\,''pin''\,''pit''\,''plug''\,''pol''\,''pooh''\,''pool''\,''pot''\,''pow''\,''pus''\,''rag''\,''rail''\,''raj''\,''ram''\,''rap''\,''rat''\,''raw''\,''reed''\,''reel''\,''regal''\,''rep''\,''repel''\,''revel''\,''rood''\,''room''\,''rot''\,''sa''\,''sag''\,''saw''\,''sub''\,''sup''\,''tab''\,''tam''\,''tang''\,''tao''\,''tap''\,''tar''\,''teem''\,''ten''\,''ti''\,''tic''\,''tide''\,''til''\,''time''\,''tin''\,''tip''\,''tog''\,''ton''\,''tonk''\,''tool''\,''top''\,''tor''\,''tort''\,''tram''\,''trap''\,''trot''\,''tub''\,''tuba''\,''tug''\,''tun''\,''vi''\,''wah''\,''war''\,''ward''\,''was''\,''way''\,''wed''\,''wolf''\,''won''\,''wop''\,''xi''\,''yah''\,''yam''\,''yap''\,''yaw''\right]$

$\mathrm{numelems}\left(\mathrm{RW}\right)$

$218$

$\mathrm{printf}\left(''\%s\backslash n''\,\mathrm{WrapText}\left(\mathrm{Join}\left(\mathrm{RW}\right)\,60\right)\right)$

AC CA IR MN NM RI TV VT abut ah am are as ate avid bad bag
ban bard bat bin bird bog bon brag bud burg bus but cit dab
dam deep deer dew dial dim diva dog don doom door drab draw
drib dual dub edit eel eh em emit en enol era eta even evil
flog flow gab gal gar garb gas gel gnat gob god golf got
grub gulp gum gut ha haw hay he ho hoop it iv ix jar keel
keep knot lag lager laid lap laud lee leek leer leg leper
lever liar lit live lone loop loot lop ma mad mar mart mat
may me meet mid mood moor mug nab nap ne net neve nib nip
nit no nob nod not now nut oat oh on pal pan par part pat
pay peed peek per pin pit plug pol pooh pool pot pow pus rag
rail raj ram rap rat raw reed reel regal rep repel revel
rood room rot sa sag saw sub sup tab tam tang tao tap tar
teem ten ti tic tide til time tin tip tog ton tonk tool top
tor tort tram trap trot tub tuba tug tun vi wah war ward was
way wed wolf won wop xi yah yam yap yaw