half-third-cousin

Half-3C:
1- Parent's half-second-cousin's child.
2- Grandparent's half-first-cousin's grandchild.
3- Great-grandparent's half-sibling's great-grandchild.
4- Person who, in relation to the other person, has zero parents, zero grandparents, zero great-grandparents and one great-great-grandparent in common.

My half-third-cousin is a good person.

quintuple-third-cousin

Quintuple-3C:
Person who, in relation to the other person, has zero parents, zero grandparents, zero great-grandparents and ten great-great-grandparents in common.

My quintuple-third-cousin is a good person.

third-cousin-11X-removed

Third-cousin-eleven-removed (3C11R).

My third-cousin-11X-removed is a good person.

co-third-cousin-in-law

Spouse's third-cousin's spouse.

My co-third-cousin-in-law is a good person.

co-third-cousin-once-removed-in-law

Spouse's third-cousin-once-removed's spouse.

My co-third-cousin-once-removed-in-law is a good person.

sesqui-third-cousin

Sesqui-3C:
Person who, in relation to the other person, has zero parents, zero grandparents, zero great-grandparents and three great-great-grandparents in common.

My sesqui-third-cousin is a good person.

triple-third-cousin

Someone who, in relation to others, has zero parents, zero grandparents, zero great-grandparents and six great-great-grandparents in common.

Triple-third-cousin.