tendency vs heterosis

tendency and heterosis both are nouns.

Word	Noun	Adjective	Verb	Adverb
tendency	Yes	No	No	No
heterosis	Yes	No	No	No

As nouns, heterosis is a hyponym of tendency; that is, heterosis is a word with a more specific, narrower meaning than tendency:

tendency: a characteristic likelihood of or natural disposition toward a certain condition or character or effect
heterosis: (genetics) the tendency of a crossbred organism to have qualities superior to those of either parent

Other hyponyms of tendency include hybrid vigor, buoyancy, electronegativity, negativity, stainability, desire.

tendency (noun)	heterosis (noun)
a characteristic likelihood of or natural disposition toward a certain condition or character or effect	(genetics) the tendency of a crossbred organism to have qualities superior to those of either parent
an attitude of mind especially one that favors one alternative over others
an inclination to do something
a general direction in which something tends to move