1.
suitable, appropriate, proper
Fitting or appropriate for a particular purpose or situation.
I'm looking for a suitable person for this job, but I can't seem to find one.
2.
random, sloppy, half-hearted
Done without much thought or care; careless or irresponsible (often negative).
適当 has two nearly opposite meanings depending on context.
SENSE 1 (positive): Suitable, appropriate
SENSE 2 (negative): Careless, sloppy
SIMILAR WORDS:
Context is key to understanding which meaning is intended.