with horizontal symmetry?
with vertical symmetry?
with 180 degrees rotation symmetry?

What are the LONGEST words in each category? (Common words are preferred.)

It's more of a challenge to answer these puzzles off the top of your head, without resorting to a Computer search. Right off the top of my head, I can think of the following words with  horizontal symmetry: BEDECKED, BOOHOOED, CEBID (a type of monkey), CHECKBOOK, CHOICE, CODEBOOK, COOKBOOK, DECIDED, DIOXIDE, DOBCHICK, EXCEEDED, HIDE, HOODOOED, ICEBOX, KEBOBBED, OBOE, OKEECHOBEE. Words with vertical symmetry are: MOM, WOW, OTTO, MAAM, MA'AM, TOOT, AHA, AA, AHA, AIA, AMA, AVA, AWA, HAH, HOH, HUH, MAM, MIM, MM, MUM, OHO, OO, OXO, TAT, TIT, TOT, TUT, UTU, VAV, WAW, AUTOMATA, AUTOTOMY, HIMATIA, HOITY-TOITY, HOMOTAXIA, MAHATMA, MAHIMAHI, MAMMATI, MAMMOTH, MATAMATA, MOTIVITY, MOUTH-TO-MOUTH, MYOMATA, MYXOMATA, OUTWAIT, TATOUAY, TAXIWAY, THATAWAY, TIMOTHY, TOMATO, TOWAWAY, WITHOUT, YAWATAHAMA (a city in Japan), and YOUTH. Upper case BID is horizontally reflective while lower case bid is vertically reflective. SWIMS has 180-degree rotational symmetry. If written in lower-case cursive, chump comes very close to having 180-degree rotational symmetry. These words with 6 or more letters have all letters rotationally symmetrical: NINONS, ONIONS, SISSOOS, SOZINS, ZOONOSIS, ZOOZOOS. All these words have both horizontal and vertical symmetry: HI, OH, IO, OHIO, OHO, and IHI'IHI (rare Hawaiian fern that now exists only in three populations, two of which are inside volcanoes). 

Edited on May 21, 2004, 11:13 am

Posted by Penny on 2004-05-21 11:11:16