Sheimos she’einam nimchakim, meaning the names of G-d that the Torah prohibits erasing. In Parshas Reeh, the Torah commands: Destroy all the places where the gentiles that you are driving out worshipped their gods, whether they are on high mountains, on hills, or beneath foliate trees. Raze their altars, smash their pillars, burn their worshipped trees, and demolish the images of their gods. Obliterate the names (of their deities) from that place (Devarim 12:2-4). The Torah then closes this passage: Do not do this to HaShem your G-d!
When the Torah states: Obliterate the names from that place. Do not do this to HaShem your G-d, it is prohibiting obliterating HaShem’s Name (Shabbos 120b; Rambam, Hilchos Yesodei HaTorah 6:1). The Gemara (Shavuos 35a) calls the names of HaShem that we may not erase sheimos she’einam nimchakim, which later became the origin of the term sheimos as a generic term to describe religious items whose discarding must be handled in a special way. Thus, either word, genizah or sheimos, may be used.
That which we call HaShem...
Although there are many expressions, such as the All-Merciful One and the Creator, which refer to HaShem, halachah recognizes a major distinction between erasing the actual holy names of HaShem, and between erasing terms that describe HaShem, but are not actual names. Erasing the actual “names” of HaShem, the sheimos she’einam nimchakim, violates a lo saaseh of the Torah, one of the 613 Mitzvos, and qualifies as a prohibition as serious as desecrating Yom Tov or eating non-kosher (see Makkos 22a).
The names of HaShem, of which there are about ten, include, among others, Elokim, Elokeinu, Keil, Shakai, Tzevakos, Eloak, and, of course, the names we call havayah and adnus. (Following the usual practice, the “k” sound is substituted somewhere in the above names, so that readers do not err and recite these holy names in vain.) Erasing any of these names is prohibited min haTorah.
Erasing attributes
On the other hand, expressions that describe attributes of HaShem — such as Rachum, All-merciful one; Chanun, He Who bestows kindness — may be erased, even when they refer to HaShem (Shavuos 35a; Rambam, Hilchos Yesodei HaTorah, 6:5). The Torah’s prohibition, do not do this to HaShem your G-d, applies only to a name of HaShem, not to an attribute that describes HaShem.
Similarly, there is no prohibition to erase His names written in other languages, such as G-d, even when spelled with the “o” in the middle (Shach, Yoreh Deah 179:11), although one must exercise care that these names do not become treated disrespectfully (Urim, 27:2, quoted also by Nesivos HaMishpat and Aruch HaShulchan ad loc.). The reason we are accustomed to spelling the name G-d, rather than with the added “o,” is because of concern that the paper it is written on might end up in the garbage or treated in some other disrespectful way.
Chaza”l
There are four places Chaza”l list the names of G-d that cannot be erased:
Alef Daled 4-letter Name Yud-Heh-Vav-HehKel א-לE-lokim א-לקיםE-loheka א-לקיךE-lohecem א-לקיכםא-היה אשר א-היהShakaiTzekos צב-אותE-lokai א-להיE-lohanu א-להינוE-koah א-לוהּBavli: Shavous 35aYerushalmi: Megilah Ch.1, halacha 5Sofrim Ch. 4 halacha 1Avos d’Rabbi Nasan, Ch. 34