argillaceo-comb. form
Stress is usually determined by a subsequent element and vowels may be reduced accordingly. Some degree of stress is always maintained on the third syllable. If the subsequent element is an existing word, it is likely to retain its original stress pattern, e.g.
argillaceo-calcareous Brit. 
/ɑːdʒᵻˌleɪʃ(ɪ)ə(ʊ)kalˈkɛːrɪəs/,
U.S. /ˌɑrdʒəˌleɪʃ(i)oʊˌkælˈkɛriəs/.
Origin: A borrowing from Latin. Etymon: Latin argillaceo-.
Etymology: < post-classical Latin argillaceo- (in e.g. argillaceo-calcareus : see argillaceo-calcareous) < classical Latin argillāceus (see argillaceous adj.); compare -o- connective.In argillaceo-calcareous at main sense after post-classical Latin argillaceo-calcareus (1774 or earlier).
1839 C. Darwin in R. Fitzroy & C. Darwin III. vi. 124 It consists of a crumbling argillaceo-calcareous rock.
This entry has not yet been fully updated (first published 1885; most recently modified version published online March 2022).
comb. form1839