This is the 4392nd most frequent Chinese word.
戒心
Vigilance or wariness to guard against harm or deception.
戒心 here refers to a cautious attitude or suspicion one holds towards strangers.
他对陌生人总是充满戒心。
He always has a guard against strangers.
戒心 in this sentence illustrates an enhanced level of cautiousness due to a past experience.
经历过那件事后,她的戒心变得更强烈了。
After experiencing that event, her sense of wariness became much stronger.
戒心 in this context represents mutual doubts or reservations in a cooperative relationship.