Hide Zen home . ... One expect true here, but result is dissapointing false postgres=# select to_tsquery('ob_1','inferences') @@ to_tsvector('ob_1','inference'); ?column? ---------- f (1 row) . ... dictionaries | ... french_ispell,french_stem} | ... inferent} (1 row) postgres=# select * from ts_debug('ob_1','inference'); alias | ... The best way is to teach ispell dictionary, the easiest way is to use synonym dictionary and put it first in the stack of dictionaries: inferences inference . ...