disquisition
Concise Oxford English Dictionary © 2008 Oxford University Press:
disquisition /ˌdɪskwɪˈzɪʃ(ə)n/
▶noun a long or complex discussion or essay.
– derivatives
disquisitional adjective (archaic).
disquisitional adjective (archaic).
– origin C15: via Fr. from L. disquisitio(n-) ‘investigation’, based on quaerere ‘seek’.
'disquisition' also found in these Oxford entries:

