Learn how to say Supineness correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word supine:
lying on the back, face upward
with the palm upward or away from the body (said of the hand)
(old-fashioned, poetic) leaning or sloping backward
mentally or morally inactive; sluggish; listless; passive
a Latin verbal noun formed from the stem of the past participle and having only an accusative and an ablative form
an infinitive in English preceded by to