Mishnayos Oholos Perek 2 Mishnah 1

אלו מטמאין באוהל, המת וכזית מן המת -and if this is difficult, an olive’s bulk of a corpse defiles, from that which is defiled from contact with the dead, all the more so, this matter is resolved in the Gemara in [Tractate] Nazir [50a, it is needed only for [the case of] a premature/non-viable birth whose limbs were not connected with sinews as it lacks an olive’s bulk of flesh.

נצל (decayed matter – liquid and coagulated portions of a corpse) – the flesh of a corpse that swelled up like a kind of ill-smelling secretion.

מלוא תרוד (A tarvad/spoon-full of dust) – a spoon, and its measurement is two handfuls.

רקב – the body of a corpse when its moisture has departed and it becomes like a kind of dust. But a handful of a a mass of earth from a grave containing parts of a decaying human body doesn’t defile other than from a corpse that was buried naked in a coffin/bier of marble and covered with a covering of marble, until it is known with certainty that there is combination of decayed matter of cloth or wood or other dirt. But a corpse that was buried in its covering or in a wooden ark or in dust, has no decayed matter. And similarly, a corpse that was buried missing a limb has no decayed matter.

אבר מן המת ואבר מן החי – as it is written (Numbers 19:16): “[And in the open, anyone who touches a person who was killed or who died naturally,” a limb that the sword separated from the living is like the corpse.

ורובע עצמות – one quarter of a Kab (i.e., 24 egg-bulks) of bones.

מרוב המנין או מרוב הבנין – My Rabbis/Teachers explained, that they are small/minute from having in them the majority of the number [of bones] and/or the majority of the frame, for even though that they don’t have the majority of the number [of bones] nor the majority of the frame, they defile.

ורוב בנינו ורוב מנינו (the greater portion of a corpse as to the size of limbs and the greater number of joints/limbs)– the majority of the frame of the body, or the majority of the number of the bones even though it is not the majority of the frame of the body, they defile, and even though there isn’t a quarter [of a Kab] in them. And the majority of the frame, such as the legs and the thighs/haunches, and the ribs [and the spine]. And the greater number of joints/limbs, such as the tops of the fingers of the hands and the feet, and similar kinds of things to them, and provided that there will be one-hundred and twenty-five limbs, they defile.