permeation per·me·a·tion (pûr'mē-ā'shən)
The process of spreading through or penetrating, as in the extension of a malignant neoplasm by continuous proliferation of the cells along the blood or lymph vessels.
permeate per·me·ate (pûr'mē-āt')
v. per·me·at·ed, per·me·at·ing, per·me·ates
To spread or flow throughout; pervade.
To pass through the openings or interstices of, as a liquid through a membrane.