Correct spelling for the English word "plasome" is [plˈɑːsʌm], [plˈɑːsʌm], [p_l_ˈɑː_s_ʌ_m] (IPA phonetic alphabet).
The hypothetical unit of protoplasm; the smallest possible particle of protoplasm, further division of which would destroy its structure and necessitate chemical change.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.