arbitrary
suvaline, meelevaldne; tinglik (2); omavoliline
olemus
Wiktionary, adj:
1. (usually of a decision) based on individual discretion or judgment; not based on any objective distinction, perhaps even made at random
2. determined by impulse rather than reason; heavy-handed
3. (mathematics) Any, out of all that are possible;
the equation is true for an arbitrary value of x