unsteady
adj.
1590s, "not firm or secure in position," from un-(1) "not" + steady, adj.. Similar formation in Old Frisian unstadich, German unstätig, Middle Dutch onstadich. Meaning "marked by irregularity" is from 1680s. Related: Unsteadily (1550s).
v.
"make unsteady," 1530s, from un-(2) "reverse, opposite of" + steady, v.. Related: Unsteadied; unsteadying.