xerosis (n.)

"excessive dryness of hair," 1706, medical Latin, from Greek xerasia "dryness," from xeros "dry, withered," from PIE root *ksero- "dry" (source also of Latin serenus "clear, unclouded," serescere "become dry;" Greek xeron "dry land;" Old High German serawen, German serben "to dry out").

word-forming element expressing state or condition, in medical terminology denoting "a state of disease," from Latin -osis and directly from Greek -osis, formed from the aorist of verbs ending in -o. It corresponds to Latin -atio.