Nope.

nope.ex

➜  ~  cat nope.ex # we can, however, redefine +,- et al. Though it's not that useful:
defmodule Nope do
  def left + right do
    left <> " ZOMG " <> right
  end
end
➜  ~  elixirc nope.ex
➜  ~  iex
➜  ~  ERL_LIBS=. iex
Erlang R16B02 (erts-5.10.3) [source] [64-bit] [smp:4:4] [async-threads:10] [hipe] [kernel-poll:false]

Interactive Elixir (0.11.1-dev) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> import Nope
nil
iex(2)> "teh drama" + "rofl"
** (CompileError) iex:2: function +/2 imported from both Nope and Kernel, call is ambiguous
    src/elixir_dispatch.erl:78: :elixir_dispatch.dispatch_import/5
    lists.erl:1339: :lists.mapfoldl/3
    src/elixir.erl:131: :elixir.eval_forms/3

iex(2)>