Lazy consensus is a method used by some OSS projects to speed up the development pace by not requiring explicit approval from other community members before someone starts implementing something new (e.g. a feature). Under lazy consensus and lack of objections is interpreted as a silent approval.
If there are too few people paying close attention to what's happening in the project, the use of this model is risky because of Warnock's dilemma. So, lazy consensus should only be used if the community is relatively active.