I have blotted out
machah  (maw-khaw')
to stroke or rub; by implication, to erase; also to smooth (as if with oil), i.e. grease or make fat; also to touch, i.e. reach to
as a thick cloud
`ab  (awb)
an envelope, i.e. darkness (or density, 2 Chron. 4:17); specifically, a (scud) cloud; also a copse -- clay, (thick) cloud, thick, thicket.
thy transgressions
pesha`  (peh'-shah)
a revolt (national, moral or religious) -- rebellion, sin, transgression, trespass.
and as a cloud
`anan  (aw-nawn')
a cloud (as covering the sky), i.e. the nimbus or thunder-cloud -- cloud(-y).
thy sins
chatta'ah  (khat-taw-aw')
an offence (sometimes habitual sinfulness), and its penalty, occasion, sacrifice, or expiation; also (concretely) an offender
shuwb  (shoob)
to turn back (hence, away) transitively or intransitively, literally or figuratively
unto me for I have redeemed
ga'al  (gaw-al')
to redeem (according to the Oriental law of kinship), i.e. to be the next of kin (and as such to buy back a relative's property, marry his widow, etc.);