Rating = Protection from Solids Protection from Liquids
IP00 = No protection No protection
IP01 = No protection condensation
IP02 = No protection water spray < 15 degrees from vertical
IP03 = No protection water spray < 60 degrees from vertical
IP04 = No protection water spray from any direction
IP05 = No protection low pressure water jets from any direction
IP06 = No protection high pressure water jets from any direction
IP07 = No protection immersion between 15cm and 1m depth
IP08 = No protection long term immersion to a specified pressure
IP10 = touch by hands (>50mm) No protection
IP11 = touch by hands (>50mm) condensation
IP12 = touch by hands (>50mm) water spray < 15 degrees from vertical
IP13 = touch by hands (>50mm) water spray < 60 degrees from vertical
IP14 = touch by hands (>50mm) water spray from any direction
IP15 = touch by hands (>50mm) low pressure water jets from any direction
IP16 = touch by hands (>50mm) high pressure water jets from any direction
IP17 = touch by hands (>50mm) immersion between 15cm and 1m depth
IP18 = touch by hands (>50mm) long term immersion to a specified pressure
IP20 = touch by fingers (>12mm) No protection
IP21 = touch by fingers (>12mm) condensation
IP22 = touch by fingers (>12mm) water spray < 15 degrees from vertical
IP23 = touch by fingers (>12mm) water spray < 60 degrees from vertical
IP24 = touch by fingers (>12mm) water spray from any direction
IP25 = touch by fingers (>12mm) low pressure water jets from any direction
IP26 = touch by fingers (>12mm) high pressure water jets from any direction
IP27 = touch by fingers (>12mm) immersion between 15cm and 1m depth
IP28 = touch by fingers (>12mm) long term immersion to a specified pressure
Rating = Protection from Solids Protection from Liquids
IP30 = tools & wires (>2.5mm) No protection
IP31 = tools & wires (>2.5mm) condensation
IP32 = tools & wires (>2.5mm) water spray < 15 degrees from vertical
IP33 = tools & wires (>2.5mm) water spray < 60 degrees from vertical
IP34 = tools & wires (>2.5mm) water spray from any direction
IP35 = tools & wires (>2.5mm) low pressure water jets from any direction
IP36 = tools & wires (>2.5mm) high pressure water jets from any direction
IP37 = tools & wires (>2.5mm) immersion between 15cm and 1m depth
IP38 = tools & wires (>2.5mm) long term immersion to a specified pressure
IP40 = tools & small wires (>1mm) No protection
IP41 = tools & small wires (>1mm) condensation
IP42 = tools & small wires (>1mm) water spray < 15 degrees from vertical
IP43 = tools & small wires (>1mm) water spray < 60 degrees from vertical
IP44 = tools & small wires (>1mm) water spray from any direction
IP45 = tools & small wires (>1mm) low pressure water jets from any direction
IP46 = tools & small wires (>1mm) high pressure water jets from any direction
IP47 = tools & small wires (>1mm) immersion between 15cm and 1m depth
IP48 = tools & small wires (>1mm) long term immersion to a specified pressure
Rating = Protection from Solids Protection from Liquids
IP50 = Limited dust ingress protection No protection
IP51 = Limited dust ingress protection condensation
IP52 = Limited dust ingress protection water spray < 15 degrees from vertical
IP53 = Limited dust ingress protection water spray < 60 degrees from vertical
IP54 = Limited dust ingress protection water spray from any direction
IP55 = Limited dust ingress protection low pressure water jets from any direction
IP56 = Limited dust ingress protection high pressure water jets from any direction
IP57 = Limited dust ingress protection immersion between 15cm and 1m depth
IP58 = Limited dust ingress protection long term immersion to a specified pressure
IP60 = Total dust ingress protection No protection
IP61 = Total dust ingress protection condensation
IP62 = Total dust ingress protection water spray < 15 degrees from vertical
IP63 = Total dust ingress protection water spray < 60 degrees from vertical
IP64 = Total dust ingress protection water spray from any direction
IP65 = Total dust ingress protection low pressure water jets from any direction
IP66 = Total dust ingress protection high pressure water jets from any direction
IP67 = Total dust ingress protection immersion between 15cm and 1m depth
IP68 = Total dust ingress protection long term immersion to a specified pressure
IP69K = Total dust ingress protection steam jet cleaning

Source: http://www.sensorsone.co.uk/ip-rating-checker.html