dubius -a -um

1. 1

   Moving in two directions alternately, vibrating to and fro, fluctuating, wavering

2. 2

   Vacillating in mind, wavering, uncertain, doubting, doubtful, dubious, irresolute, undetermined

   = incertus= suspensus= vagus= anceps ↔ fixus↔ prōmptus↔ indubius

3. 3

   Precarious, dangerous, critical, difficult, adverse, doubtful, in doubt

   = perīculōsus= īnfēnsus= anceps= capitālis

4. 4

   Changeable, uncertain