doubtful (adjective) doubtful: questionable, unclear
Detalii: a person is capable of doubting, whereas a thing is dubitable; dubious, unlike doubtful, carries the connotation of suspicion
Sinonime: aid, associate with, be a participant, be a party to, be into, chip in, come in,
compete,
concur,
cooperate,
engage, engage in, enter into, get in on, get in on the act, go into, have a hand in, have to do with, join in, latch on, lend a hand,
partake,
perform,
play,
share, sit in on, sit in,
strive, take an interest in, tune in
Antonime: observe,
watch