Hi,
Yes, longest match means most specific match. CAM looks for exact match, but when you do route lookup for a destination say 10.10.10.1, not necessary you would have route in routing table with exact match (/32 prefix 10.10.10.1/32) but instead of that you may have 10.10.0.0/16 or 10.10.10.0/24 or 10.10.10.0/30. And you search for longest match route. In this example 10.10.10.0/30 would be selected for the route lookup of destination 10.10.10.1. This can be done with TCAM but not CAM
You can refer below link as well for more detail discussion.
https://supportforums.cisco.com/discussion/10414976/cam-vs-tcam
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Regards,
Akash