at its core
- essentiallyAt its core nature
- fundamentallyAt the core level
- heartCirculatory system's pump
- nucleusCentral controlling part
- cruxMost important point
essence · root · center · soul · bedrock · foundation · underlying · intrinsically · basic · deep down · marrow · kernel · pith · gist · nub · quintessence · backbone · innermost
depth/centrality
at its coreon the surface
In apparent aspect only
superficially · on the outside · outwardly · externally · tangentially
authenticity/truth
at its coreon the surface
In apparent aspect only
superficially · on the face of it · outwardly · at first glance · ostensibly
centrality vs. periphery
at its coreat the edges