  Lead zirconate (PbZrO$_3$) is considered the prototypical antiferroelectric
material with an antipolar ground state. Yet, several experimental and
theoretical works hint at a partially polar behaviour in this compound,
indicating that the polarization may not be completely compensated. In this
work we propose a simple ferrielectric structure for lead zirconate.
First-principles calculations reveal this state to be more stable than the
commonly accepted antiferroelectric phase at low temperatures, possibly up to
room temperature, suggesting that PbZrO$_3$ may not be antiferroelectric at
ambient conditions. We discuss the implications of our discovery, how it can be
reconciled with experimental observations and how the ferrielectric phase could
be obtained in practice.
