Yes
It is possible. I would first define all the individual rules which describe a Series of Words followed by an Acronym Definition (SOWFBAAD), then stitch these rules together in a define statement.
For example if you were looking for an email address you could use this Perl Compliant Regular Expression (PCRE) which first defines all the rules from RFC 5322 then looks for things which look like email addresses:
(?x)
(?(DEFINE)
(?<addr_spec> (?&local_part) @ gbase\.tt )
(?<local_part> (?&dot_atom) | (?"ed_string) | (?&obs_local_part) )
(?<domain> (?&dot_atom) | (?&domain_literal) | (?&obs_domain) )
(?<domain_literal> (?&CFWS)? \[ (?: (?&FWS)? (?&dtext) )* (?&FWS)? \] (?&CFWS)? )
(?<dtext> [\x21-\x5a] | [\x5e-\x7e] | (?&obs_dtext) )
(?<quoted_pair> \\ (?: (?&VCHAR) | (?&WSP) ) | (?&obs_qp) )
(?<dot_atom> (?&CFWS)? (?&dot_atom_text) (?&CFWS)? )
(?<dot_atom_text> (?&atext) (?: \. (?&atext) )* )
(?<atext> [a-zA-Z0-9!#$%&''*+/=?^_`{|}~-]+ )
(?<atom> (?&CFWS)? (?&atext) (?&CFWS)? )
(?<word> (?&atom) | (?"ed_string) )
(?<quoted_string> (?&CFWS)? "" (?: (?&FWS)? (?&qcontent) )* (?&FWS)? "" (?&CFWS)? )
(?<qcontent> (?&qtext) | (?"ed_pair) )
(?<qtext> \x21 | [\x23-\x5b] | [\x5d-\x7e] | (?&obs_qtext) )
# comments and whitespace
(?<FWS> (?: (?&WSP)* \r\n )? (?&WSP)+ | (?&obs_FWS) )
(?<CFWS> (?: (?&FWS)? (?&comment) )+ (?&FWS)? | (?&FWS) )
# (?<ccontent> (?&ctext) | (?"ed_pair) )
(?<ccontent> (?&ctext) | (?"ed_pair) | (?&comment) )
(?<ctext> [\x21-\x27] | [\x2a-\x5b] | [\x5d-\x7e] | (?&obs_ctext) )
# obsolete tokens
(?<obs_domain> (?&atom) (?: \. (?&atom) )* )
(?<obs_local_part> (?&word) (?: \. (?&word) )* )
(?<obs_dtext> (?&obs_NO_WS_CTL) | (?"ed_pair) )
(?<obs_qp> \\ (?: \x00 | (?&obs_NO_WS_CTL) | \n | \r ) )
(?<obs_FWS> (?&WSP)+ (?: \r\n (?&WSP)+ )* )
(?<obs_ctext> (?&obs_NO_WS_CTL) )
(?<obs_qtext> (?&obs_NO_WS_CTL) )
(?<obs_NO_WS_CTL> [\x01-\x08] | \x0b | \x0c | [\x0e-\x1f] | \x7f )
# character class definitions
(?<VCHAR> [\x21-\x7E] )
(?<WSP> [ \t] )
)
((?&addr_spec))
Of course this expression does use recursion which doens't play well with many flavors of regex. To resolve that, you could simply comment out the ccontent and uncomment comment the other ccontent providing you accept that the expression will no longer find recursive comments.
However
Constructing this as a regex alone may leave you with an expression which is incredibly difficult to read, debug, or modify later. So you would probably be better off looping through a list of SOWFBAAD definitions.