abscissa /-sisˈə/, also absciss or abscisse /abˈsis/ noun (pl abscissae /ab-sisˈē or -sisˈī/, abscissˈas or abˈscisses) (mathematics)

1. The intercept between a fixed point and the foot of an ordinate
2. The x-co-ordinate in analytical geometry

abscissˈin noun same as abscisin (see under abscise)

abscission /-sizhˈən/ noun

1. An act of cutting off, or the state of being cut off
2. A figure of speech in which words demanded by the sense are left unsaid, the speaker stopping short suddenly (rhetoric)
3. Organic shedding of a part (eg a leaf or fruit) (botany)
4. Liberation of a fungal spore by breakdown of part of its stalk (botany)

absciss layer or abscission layer noun (botany)

A layer of parenchymatous cells through which a leaf, branch or bark scale separates off