Rashi: It is an expression of Kele (incarceration). Radak - the last letter of the root is Hei, like "Lo Yichleh Mimcha" (Bereishis 23:6), "Asher Kelisini" (1:25:33). Also "Malu Sochecha Chamas" and "v'Nasu Es Kelimasam" (Yechezkel 28:16, 39:26) are as if there were an Aleph (in Malu and v'Nasu). Hei and Aleph are often interchanged.