sei'ar lavan, umichyat basar (Levit. 13:10) ('a white hair u-living flesh') R' Saadya Gaon and Rashi both interpret the Vav (which is read u-) to mean 'or'; this interpretation is based on the comment of the Sifre.

An irregular verb

hukabeis oto (Levit. 13:56) ('it being laundered') Leshon Chaim (a book explaining grammatical points in Rashi) points out that this verb is identical in form with huledet (Gen. 40:20) and the following is his explanation:

It is laundered by others, that is to say the verb hukabeis is a merger of two conjugations, as the infinitive of the root chaf beit samech in the Pi'el conjugation is kabeis, and in Hof'al its root is huchbas, so it is evident that it [hukabeis] is a merger of two conjugations Pi'el and Hof'al. [As in the case of huledet] there is a particle et after hukabeis, even though after Hof'al the particle et should not occur. As hukabeis is formed by a merger of the two conjugations, and after Pi'el et can occur, [this is no longer a problem] (based on Gur Aryeh).

What does tsipor mean? tsiporim (Levit. 14:4) In the opinion of Rashi (as explained by Ramban) the word tsipor is generic for any kind of bird. R' A. ibn Ezra states so explicitly. Ramban disagrees and argues that it means small birds that chirp and quotes many verses that support this interpretation. Interestingly in English 'sparrow' has both meanings (OED).

In The Word (p. 3) the author I. E. Mozeson informs us that the similarity between the English word 'sparrow' and the Hebrew word tsipor led him to examine further similarities between the two languages. He is suggesting monogenesis of language with Hebrew (or something very like it) as the original language. The whole of his book presents interestingly similar words without discussing the routes that these words may have taken to move from Hebrew to English or in some cases to other languages. However the large number of examples strengthens his argument. Many scientific theories, which later became widely accepted, started off as ideas less well documented than this.

Which letters absorb the Tav of the Hitpa'el?

lamitaheir (Levit. 14:4) ('for the one who becomes purified') R' A. ibn Ezra states 'It is of the same linguistic format as mit'haleil (Proverbs 25:14) [i.e. it is of the Hitpa'el conjugation] and the Tav of the Hitpa'el is absorbed by way of the Dagesh in the Tet.' This also occurs with midabeir (Num. 7:89) and vehitamhu (Hab. 1:5) as some of the commentaries point out. Thus we have found this manifestation in cases of words whose roots commence with Dalet, Tet and Tav. Is there a general rule that covers all these cases?

Sefer Yetzira (an ancient work) classifies the letters of the Hebrew alphabet into five groups according to their point of articulation in the vocal tract. One of these groups is the Linguals: Dalet, Lamed, Tet, Nun, Tav; that is, those letters which are articulated with the tip of the tongue touching the alveolar ridge (behind and above the front teeth). Another group of letters that can be shown to have significance in Hebrew is Bet, Gimmel, Dalet, Chaf, Peh, Tav, (with Dagesh) and Alef, Tet, Kuf. These are Plosives (or Stops). It is only among them that one can find letters (without a vowel) which occur in the Tenach at the end of a word following a letter which has a Sheva: vayishb (Num. 21:1); neird (Song. 4:14); vayevk (Gen. 27:38 etc.); tosp (Prov. 30:6); va'eisht (Gen. 24:46); cheit (Levit. 19:17 etc.); kosht (Prov. 22:21); vayashk (Gen. 29:10 etc.). Though I have not found this classification in traditional grammar books, it is listed in the section on Phonology at the back of the Even Shoshan Dictionary.

Dalet, Tet and Tav belong to both groups. They are articulated by placing the tongue on the alveolar ridge, and they are Plosives. Hence they are phonetically alike, and when proximate to the Tav of the Hitpa'el they absorb it. The rule is: the letters that are both Linguals and Plosives, absorb the Tav of the Hitpa'el.