nerd
/nərd/
INFORMAL
noun
1.
a person who is extremely enthusiastic and knowledgeable about a particular subject, especially one of specialist or niche interest.
"the executive is an unabashed film nerd"
verb
engage in or discuss a technical field obsessively or with great attention to detail.
"his engineering background means he tends to nerd out a bit on the numbers"
where was my enthusiasm?
or my extensive knowledge?