autophagosome

noun

au·​to·​phago·​some ˌȯ-tō-ˈfag-ə-ˌsōm 

: a double membrane-bound vesicle that encloses cellular constituents and fuses with lysosomes which digest these cellular constituents during autophagy

The autophagosome does not bud off from preexisting organelles but, rather, is formed by a dynamic process of membrane expansion.

—Daniel J. Klionsky, The New England Journal of Medicine

During autophagy, a portion of cytoplasm is sequestered into an autophagosome: this then fuses with the lysosome, and the cytoplasm-derived materials are degraded.

—Satoshi Tsukamoto et al., Science