The word "Chupah" appears in Tanach in Yeshayahu (4:5), and Yoel (2:16). Its
root is the word "Chofeh," meaning "cover." It seems, therefore, that
"Chupah" refers to something which "covers" the Kalah in some manner. The
Radak (in Yoel) is uncertain whether the Chupah of a Kalah is a roofed room,
or ornaments that the Kalah covers herself with. Let us try to find out what
type of covering constitutes the Chupah to which the Mishnah refers, and how
it effects Nesu'in.
(a) We learned earlier (see Insights to 48:2) the view of the GE'ONIM (cited
by the RAN on 1a according to the pages of the Rif), which many understand to
be the opinion of the RAMBAM (Hilchos Ishus 10:1). Their view is that Chupah
means that the Chasan secludes himself with the Kalah to the absolute
exception of anyone else (Yichud). The Rambam adds that the woman must be
Ra'uy l'Bi'ah at the time. According to this view, it seems that Chupah
accomplishes Nesu'in the same way that Bi'ah accomplishes Nesu'in -- it is
the beginning of an intimate relationship of Ishus. (TOSFOS, Yoma 13b DH
l'Chada, seems to accept this understanding of Chupah with regards to an
Almanah, but not with regards to a Besulah.)
According to this understanding, the word Chupah might mean that after this
display intimacy, the husband feels responsible to be his wife's protector
who "covers" or shields her. (This is also the way the Perishah EH 61:2
interprets the word "Chupah.")
(b) We discussed earlier (Insights to 48:2) that there are many proofs
against this opinion, and it seems that the Rambam himself does not require
an actual Yichud that is Ra'uy l'Bi'ah. Rather, Chupah means that the woman
is (1) brought into the husband's house "l'Shem Nesu'in," for the purpose of
Nesu'in, (2) in a semi-private manner. (That is, they may be still visible to
others, who watch them from, the outside.) This is the way the BEIS ME'IR
(EH 55:1) explains the Rambam, and the MAGID MISHNAH (end of Ishus 10:6)
seems to interpret the Rambam this way as well (see also BEIS SHMUEL EH 57:2
and BACH EH 61).
The RAN (Kesuvos 1a, and VILNA GA'ON EH 55:9) also defines Chupah as
"bringing the Kalah into the Chasan's house l'Shem Ishus" (but he does not
seem to require any type of Yichud). The Ran adds that the source for this
Kinyan in the Torah is the verse regarding Hafaras Nedarim, "v'Im Beis Ishah
Nadarah" (Bamidbar 30:11), which describes the married woman as "in the house
of her husband." The TUR, EH 61, defines Chupah as Yichud (but he does not
seem to require that the Kalah be brought into his house -- see DERISHAH
61:1, PERISHAH 61:2).
The Rambam, Ran and Tur all seem to be defining Chupah in a similar, if not
identical, fashion. According to their understanding, the "covering" of
Chupah might mean that the Chasan covers the Kalah with his home -- he puts a
roof over her head, so to speak.
(c) Others explain that Chupah is a symbolic act which shows that the Chasan
is designating the Kalah for himself and is about to bring her into his home
permanently to be his wife. This act could be an act of covering the Kalah
("Chofeh") in some way.
The Tashbetz (Tashbetz Katan #461) and the REMA (EH 55:1) describe Chupah a
cloth or curtain spread over the heads of the Chasan and Kalah -- in short,
what we refer to today as Chupah. This canopy might also be reminiscent of
Kabalas ha'Torah, where Hashem was "wedded" to the Bnei Yisrael by holding
the mountain over the people in an act of "Chupah." (In fact, Tashbetz [ibid.
#465] writes that "all of the customs of the Chasan and Kalah are learned
from Matan Toah, where Hashem appeared to us like a Chasan coming to greet
the Kalah, Bnei Yisrael"; see Rashi, Shemos 19:17.)
The ME'IRI (Kesuvos 7b) writes that the practice was to take a corner of the
head covering of the Kalah and cover the Chasan's head with it. The YAM SHEL
SHLOMO (Kesuvos 1:17) writes that they covered the Kalah's head with the
Chasan's Talis. (An allusion to this is to be found in the Gemara in Kidushin
(18b) which refers to marriage as "spreading one's Talis" over one's wife.) A
hint to such a practice can be found in the verse in Ruth (3:9), where Ruth
requests of Boaz that he "spread his garment over your maidservant."
TOSFOS in Yoma (13b) writes that covering the Kalah's head with the veil
("Hinuma") is Chupah (at least for a Besulah). The Hinuma is a sign that she
is now a married woman. An allusion to this can be found in the verse that
says that when Rivka saw Yitzchak as she was brought to him to marry him, she
covered her face with a veil (Bereishis 24:65).
(The BA'AL HA'ITUR (Birchas Chasanim, #2) writes that Chupah means bringing
her into his house once he has decorated it in her honor, or into a pretty
bridal canopy. He seems to also be following the view that Chupah is a
symbolic act which shows that he is about to take her into his house
permanently as his wife.)