Adequate ~ sufficient ~ enough

Adequate, sufficient and enough are slightly different in meaning. If something is adequate, there is enough of it, but only just enough. If there is sufficient quantity of something, this suggests that there is as much of it as you need. Usage of these adjectives often denotes quantity rather than quality, whereas appropriate and suitable suggest a qualitative response to something. Study the following examples:

• The pay was adequate, but it certainly wasn't generous. The rate of pay - £5.50 an hour - was barely adequate to raise a family on.
• His answer to the question was adequate but it wasn't developedsufficiently to gain high marks.
• The Prime Minister gave an inadequate reply to the journalist's question. 
• The action taken to combat the spread of malaria was quite inadequate.                  
• There were not enough seats for all the guests. The supply of seats was quite inadequate.
• There was easily enough food for every one. There was a sufficientamount of food.
• There was insufficient evidence to convict him of house-breaking.