"given to following leaders," 1630s, from Latin sequac-, stem of sequax "that follows, following, seeking after," from sequi "to follow" (from PIE root *sekw- (1) "to follow") + -ous. Related: Sequaciously; sequaciousness; sequacity (1620s).
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit sacate "accompanies, follows;" Avestan hacaiti, Greek hepesthai "to follow;" Latin sequi "to follow, come after," secundus "second, the following;" Lithuanian seku, sekti "to follow;" Old Irish sechim "I follow."
word-forming element making adjectives from nouns, meaning "having, full of, having to do with, doing, inclined to," from Old French -ous, -eux, from Latin -osus (compare -ose (1)). In chemistry, "having a lower valence than forms expressed in -ic."