Across two companies in two sectors of the marketplace (defense/finance) we've used the term Subject Matter Expert for this. It gets used so much (in the US, or at least the NorthEast part of the US) we even call it "SME" (pronounced 'smee"), although for clarity I'd skip the acronym on a resume.
I've put that on my own resume, and seen it on others. It distingushes from "Technical Lead" for me in the following ways:
Technical Lead - may or may not be the expert on all aspects of the project or the work of the team that reports to him. More likely, he knows some depth about some things and less about others, but has outstanding leadership skills so he can rally the team, and match work and people to the best effect.
Subject Matter Expert - high level individual contributor, who is the go-to guy on certain key technical areas. Can be either in the solution domain or the problem domain. Has strong teaching/mentoring capabilities, but may not be doing managerial/leadership stuff. In fact, the purest of SMEs may be people you do not WANT to task with team leadership, because then they don't have as much time as they should have to keep abreast of the state of the art and mentor people through the really hard questions.
When I hear lead, I suspect the person has to skim the surface of at least a few technical areas. When I hear SME, I feel sure the person has made a deep dive.
In particular, annotate it with areas. For example, I call myself a Subject Matter Expert on Java Web Security and PKI. I would be relunctant to believe a resume that didn't put some reasonable qualifications down - for example, all fo JEE is pretty broad, more likely a SME is well-versed in particular APIs.