zygo-, zyg-, -zygous; zygomatico- +

(Greek: yoke, forming pairs; joined, union; or indicating a relationship to a junction; meaning a yoke or crossbar by which two draft animals; such as, oxen could be hitched to a plow or wagon)

multiplex zygote (s) (noun), multiplex zygotes (pl)
A fertilized ovum which does not possess a gene for a given dominant character.
phenozygous (adjective), more phenozygous, most phenozygous
Pertaining to the structure of a head that has a narrow cranium as compared with the width of the face, so that when the skull is seen from above, the zygomatic arches are visible, that means that the bones form a bridge between the cheekbones and the temporal bones on each side of the bony skeleton of the head of vertebrates: In her biology book for school, it was interesting to see a photo of a skull that had a phenozygous form.
simplex zygote (s) (noun), simplex zygotes (pl)
A fertilized ovum which possesses only one gene for a given dominant character.
squamozygomatic (adjective) (not comparable)
Referring, or pertaining, to both the squamosal and zygomatic (malar or cheek bone) bones: Lynn read about the squamozygomatic bone or center of ossification, which is found in some fetal skulls.
syzygial (adjective) (not comparable)
Relating to the alignment of three celestial bodies in a straight line: The moon is syzygial when it is in opposition to the earth and sun and full or new.
syzygiology (s) (noun) (no pl)
The study of interrelationships, or interdependencies, especially of the whole: Syszgiology deals with the total unit as opposed to the study of separate parts or isolated functions.
syzygy (s) (noun), syzygies (pl)
1. The conjunction and fusion of organs without loss of identity: Syzygy is the uniting or merging of body parts of an animal.
2. The condition of the moon, sun, and earth appearing in a straight line: When the eclipse took place, Jane saw a syzygy in the sky for the first time!
zygal (adjective), more zygal, most zygal
Referring to something shaped like a yoke: The stem joining the two sections of the brain fissure had the zugal form of the letter H.
zygantrum (s) (noun), zygantra (pl)
A fossa, which is a cavity or depression, or posterior surface of the neural arch of the vertebrae or spines of snakes: The zygantrum connects vertebrae segments not only in limbless scaly and elongated reptiles, but also in certain lizards.
zygapophyseal (adjective) (not comparable)
A reference to a bilateral small flat projection of a vertebra (zygapophysis): Susan read in her biology book that the zygapophyseal process of a vertebra occurs in pairs and connects or intertwines with the one above and below.
zygapophysis (s) (noun), zygapophyses (pl)
One of the articular processes of a vertebra, of which there are usually four; two anterior (in front) and two posterior (in the back): The backbone is made more stable due to projections which lock with a zygapophysis on the adjacent vertebra.
zygion (s) (noun), zygia (pl)
A craniometric and cephalometric landmark, being the most laterally situated point on either zygomatic arch.

The "zygomatic arch" is that part of the temporal bone of the skull that forms the prominence of the cheek.

zygodactyl, zygodactylous (adjective) (not comparable)
A description of the feet of birds in which the second and third toes face forward and the first and fourth toes face backward: While walking in the woods, Samantha saw a cuckoo that had zygodactyl digits on its feet, like the photo in her biology book.
zygodactylism (s) (noun) (no pl)
1. A condition of certain climbing birds, having the toes of each foot arranged in pairs, with two toes in front and two behind: After reading about zygodactylism in her biology book, Jane found out that woodpeckers, owls and most parrots have such toe arrangements.
2. This term is sometimes used to designate simple syndactyly (webbing between adjacent digits so they are more or less completely attached), as distinguished from syndactyly in which there is bony fusion between the phalanges of the digits involved and usually occurring in the hand between the third and fourth digits and in the foot between the fourth and fifth.
zygodactyly (s) (noun) (no pl)
An arrangement of digits in birds, with two toes facing forward (digits two and three) and two back (digits one and four): Zygodactyly is most common in arboreal species, particularly those that climb tree trunks or clamber through foliage.

Zygodactyly occurs with woodpeckers, flickers, nuthatches, and parrots.