Richard Suchenwirth - i18n stands for that word with "i" in front, "n" at the end, and 18 letters in between - internationalization, adapting software to non-English language environments.
Here's a little script that shows you what exotic characters your system has available (Tcl can process all of the Unicode characters, but for displaying the fonts must also be reachable). It creates a text window and tries to show some sample text for the specified languages:
pack [text .t] .t insert end " Arabic \uFE94\uFEF4\uFE91\uFEAE\uFECC\uFEDF\uFE8D\uFE94\uFEE4\uFEE0\uFEDC\uFEDF\uFE8D Chinese \u4E2D\u56FD\u7684\u6C49\u5B57 Greek \u0395\u03BB\u03BB\u03B7\u03BD\u03B9\u03BA\u03AC\ \u03B3\u03BB\u03CE\u03C3\u03C3\u03B1 Hebrew \u05DD\u05D9\u05DC\u05E9\u05D5\u05E8\u05D9\ \u05DC\u05D9\u05D0\u05E8\u05E9\u05D9 Japanese \u65E5\u672C\u8A9E\u306E\u3072\u3089\u304C\u306A,\ \u6F22\u5B57\u3068\u30AB\u30BF\u30AB\u30CA Korean \uB300\uD55C\uBBFC\uAD6D\uC758 \u3CA2\u3498 Russian \u0420\u0443\u0441\u0441\u043A\u0438\u0439\ \u044F\u0437\u044B\u043A "
No font or size are specified, so you see the pure defaults (and notice how Tk manages to find characters). You can then configure the text widget for the fonts you'd like to see.
See also A little Unicode editor - The Lish family