WordNet sense 1 (lying beyond what is openly revealed or avowed (especially being kept in the background or deliberately concealed)):

subterranean, subterraneous

WordNet sense 2 (secret or hidden; not openly practiced or engaged in or shown or avowed):

covert

WordNet sense 3 (far apart in relevance or relationship):

distant

WordNet sense 4 (coming at a subsequent time or stage):

future, later

WordNet sense 5 (following in time or order):

subsequent