cyt/o, hist/o
cyt/o means cell and hist/o means tissue (Greek).
"SIGH-toh / HISS-toh." Coach: "Cyt is a cell; hist is tissue made from cells."
Examples: cytology, cytoplasm, cytotoxic, cytopenia, leukocyte.
Also: erythrocyte, histology, histopathology, histochemistry, histocompatibility.