‘Upminster’ means the large church on high ground.
It was recorded as Upmynstre in 1062 and as Upmunstra in Domesday Book of 1086, from Old English upp and mynster. The high ground is that of St Laurence’s parish church, above the valley of the River Ingrebourne. Another explanation is that ‘up’ placed the church in relation to one at Barking or Tilbury in Anglo-Saxon times.