Suteki - Adjective, Japanese in origin
Suteki is japanese for "beautiful". Like some other Japanese words, fans of Japanese culture will sometimes use this word in their english sentences.
A distinction must be made between "Suteki" and "Kawaii".
"Kawaii" is cute, a less serious word.
"Suteki" is beautiful, a word with more impact and used in more serious context.
Kawaii would apply to a plush toy, a figurine, or a costume.
Suteki would apply to a gorgeous female, a situation which is extremely nice, or something very touching such as falling in love.
"Suteki!" (Upon seeing a swimsuit photo of a beautiful girl)
"Suteki da ne?" (Beautiful, isn't it?)
suteki is often used by the japanese and others who know the language to mean "stylish" or "fancy" in extreme conditions. it's more widely used as "stylish" than "beautiful" or "cute".
"Oh, that shirt is so suteki!"
"suteki no t-shatsu desu ne!"
(that shirt is stylish you know)