intromission

Among the tuatara’s unusual reptilian traits are the relatively simple structure of its heart and lungs, the somewhat froggy style of its gait and the absence of any sort of male intromission organ, or penis.

From New York Times ● Nov. 22, 2010

Her first intromission in politics--but I must not tell you that story, the authorities have decided you are to hear it otherwise and from a livelier narrator.

From David Balfour, Second Part Being Memoirs Of His Adventures At Home And Abroad, The Second Part: In Which Are Set Forth His Misfortunes Anent The Appin Murder; His Troubles With Lord Advocate Grant; Captivity On The Bass Rock; Journey Into Holland And France; And Singular Relations With James More Drummond Or Macgregor, A Son Of The Notorious Rob Roy, And His Daughter Catriona by Robert Louis Stevenson

It may be urged, and with great plausibility, that there may be intromission without fraud; which, however true, will by no means justify an occasional and arbitrary relaxation of the law.

From The Works of Samuel Johnson, Volume 05 Miscellaneous Pieces by Samuel Johnson

It appears that a series of occurrences, involving his happiness, honour and dignity at once, can be traced to your Excellency's intromission in his affairs.

From The Spanish Jade by William Henry Hyde

The clumsy, well meant intromission of third parties had only the effect of substituting Lockhart’s friend Christie in the broil for Lockhart himself.

From Life of John Keats His Life and Poetry, his Friends, Critics and After-fame by Sidney Colvin