(1) To sustain, or to support, or to hold.
(2) Rein.
(3) Charioteer.

(4) Self control. See also   Ashtaang Yog
This self control is of 10 types - (1) Brahmcharyan (celibacy), (2) Dayaa (kindness), (3) Kshaanti, (4) Daan (charity), (5) Satya (truth), (6) Aarjav (straight forwardness), (7) Ahinsaa (non-violence), (8) Asteya (not stealing), (9) Maadhurya (sweet speech), and (10) Dam.

According to Agni Puraan, p 335, Yam is of 5 types - (1) Ahinsaa - non-violence, (2) Satya - truth, (3) Asteya - not stealing, (4) Brahmcharya - and (5) A-Parigraha - not collecting anything.

(5) Yam is one part of Patanjali Yog Sootra

(6) Yam Raaj
Yam Raaj is the Devtaa of Death. He is the one who keeps the account of the Paap and Punya of all the creatures through his assistant Chitrarath. When people die, he prescribes Swarg (Heaven) or Narak (pleasures or pains and sorrows) according to their Karm. He gives the dead person a resting place and prepares an abode for him. It is curious that though Yam rules the dead, he is not feared but loved because of the belief that upon death a person joins his ancestors in Heaven ruled by him.

Yam is also regarded as Dharm Raaj or god of justice. In this capacity he could punish the evil doer also and hence later he came to be feared. He is also mentioned in Rig Ved as one of the sons of Vivaswaan, a human. He is considered as one of the atmospheric divinities, perhaps because he was the first one to successfully reach the blessed celestial spheres. Yam and his sister Yamee are also found in the Paarasee scriptures as Yim and Yimeh.

In Hindu incest (marriage) between real sister and brother is considered a great sin. In order to illustrate this, a dialog between Yam and Yamee is described in Rig Ved, wherein Yamee wants to seduce her brother but Yam successfully repulses her by pointing out the sinfulness of such a course. [Rig Ved, 10-10]
[Aangiras, p 298-299]

According to Bhaagvat Puraan, 5/8, there are four Lokpaal, one for each direction - Indra is for east, Yam Raaj is for south, Varun is for west, and Chandramaa is for north. To the east of Meru Parvat is Indra's Devadhaanee Puree, to the south is Yam Raaj's Sanyamanee Puree, to the west is Varun's Nimlochanee Puree, and to the north is Chandramaa's Vibhaavaree Puree.

There is an interesting Shlok about Yam
yam vaidya kayormadhye yam shreshtho na vaidyakah
yamah (or Yamastu) praanaan harati vaidyah praanaan dhanaani cha
It means that Yam is better between Yam and Vaidya, because Yam only takes life, while Vaidya takes both life and money.