Any boon which comes into one's hands by good luck.
Food miraculously produced for the Israelites in the desert in the book of Exodus.
The sugary sap of the manna gum tree which oozes out from holes drilled by insects and falls to the ground around the tree.http://www.museum.vic.gov.au/forest/plants/gum.html
An offset to the temperature setting of a thermostat to cover a period when more or less heating is required than usual.
An obstacle, delay, disadvantage, blow (an adverse event which retards or prevents progress towards a desired outcome)
A step-like recession in a wall.
The required distance between a structure and a road.