Any device that connects two dissimilar media into one network is a bridge.

With this constrained definition, it would probably meet the definition of a translational bridge. I don't think that there's any standard associated with the definition of translational bridging, so while a Token Ring-to-Ethernet bridge would clearly fall under that definition, not sure that a 10Mbps-to-100Mbps speed-sensing Ethernet bridge would.

All I mean to say is that a device does not have to connect dissimilar media to meet the definition of a bridge. There have been plenty of single-speed, single media, same-frame-format bridges. Switches are just evolved intelligent multi-port bridges, making definitions progressively more muddy.