Entry-level is relative to current competition.

A few years back, semipro/professional level cameras were lacking many features that even entrylevel cameras have now; for example auto-ISO, sensor cleaning mechanisms etc.

Here's a list of classic entry-level features that's remained more or less true for since around 2003 - when the worlds arguably first entry-level DSLR, the Canon EOS 300D was introduced:

• APS-C sized sensor (smaller than full frame)
• Small, lightweight plastic camera body (as opposed to magnesium alloy, for example)
• Very rarely has weather sealing
• Relatively slow and limited burst capabilites
• Inability to use some advanced functions such as mirror lock-up, setting of second or firstcurtatin flash sync etc (if you don't know what it is, you'll probably not miss it)
• Slower to operate; more need to go into menus instead of direct-access buttons. Compare for example the dual wheel design of Canon's 10D-70D lineup, whereas their entry-level has buttons, making it much more tedious to scroll through photos
• Shutter not rated; prolevel cameras often have shutters rated to be able to snap 150,000+ photos
• Low price

It's interesting to note though, that entry-level or semi-pro cameras actually deliver many functions before they make their way into the semipro/pro level cameras. That's probably because they may seem superficial, or toy-like at first, or just not be necessary/appealing at the semipro/pro level, like swivel screen, GPS or WiFi. Eventually though, they seem to make their way into the semipro/pro cameras as well (less likely the more 'pro' the camera is rated)