Welcome, George; the on-line Compact Oxford English Dictionary gives these def.'s:

ortho-

• combining form 1 straight; rectangular; upright: orthodontics. 2 correct: orthography.

— ORIGIN from Greek orthos ‘straight, right’.


meta-
(also met- before a vowel or h)

• combining form forming words referring to: 1 a change of position or condition: metamorphosis. 2 position behind, after, or beyond: metacarpus. 3 something of a higher or second-order kind: metalanguage.

— ORIGIN from Greek meta ‘with, across, or after’.


para-
(also par-)

• prefix 1 beside; adjacent to: parathyroid. 2 beyond or distinct from, but comparable to: paramilitary.

— ORIGIN from Greek para ‘beside, beyond’.

Goodness gracious--aren't you glad you don't have to learn these?:
http://www.saskschools.ca/curr_content/creeunit/possessive_form_cousins.htm

Hmm--looks like the antonym of orthocousin may in fact be cross cousin; see the second paragraph:
http://ourancestry.com/cousins.html