"erratic behavior" "fickle weather" "mercurial twists of temperament" "a quicksilver character, cool and willful at one moment, utterly fragile the next"
having no fixed course;
"an erratic comet" "his life followed a wandering course" "a planetary vagabond"
likely to perform unpredictably;
"erratic winds are the bane of a sailor" "a temperamental motor; sometimes it would start and sometimes it wouldn't" "that beautiful but temperamental instrument the flute"
