BlankSequence

__ matches any sequence of one or more expressions.

__head matches any sequence of one or more expressions, each with a Head of head.

Attributes[BlankSequence] := {Protected}

Simple examples

In[1]:= MatchQ[a + b + c, a + b + __]
Out[1]= True

In[2]:= MatchQ[a + b + c, a + b + c + __]
Out[2]= False

With head assertions:

In[1]:= MatchQ[a*b, __Symbol]
Out[1]= False

In[2]:= MatchQ[a*b, x__Symbol]
Out[2]= False

In[3]:= MatchQ[a, __Symbol]
Out[3]= True

In[4]:= MatchQ[a*b, x__Times]
Out[4]= True

In[5]:= MatchQ[a*b, x__Plus]
Out[5]= False

In[6]:= MatchQ[a + b, x__Plus]
Out[6]= True