Ambitransitive verb

An ambitransitive verb is a verb which can be used either as a transitive verb or intransitive verb without any morphological marking of its valence alternation.

Semantic groups
The main semantic groups of verbs which tend to be labile cross-linguistically are:

1. motion verbs 2. destruction verbs 3. phasal verbs (Bulgarian zapochvam 'begin') 4. sound emission verbs (Russian igrat' 'play', Bulgarian svirja 'play', German spielen 'play', French sonner 'sound, play')

Examples
English:

1) Malcolm is reading a book. (read is transitive) 2) Malcolm is reading. (read is intransitive)

S/A aligned ambitransitive verbs
German:

3) Inge liest ein Buch. || (transitive lesen has A and P) ‘Inge is reading a book.’  4) Inge liest || (intransitive lesen has an agent-like S) ‘Inge is reading.’ || 5) *Ein Buch liest. || (intransitive lesen cannot take a patient-like S) *‘A book is reading.’ ||

S/P aligned ambitransitive verbs
English:

6) Carl opens the door. (transitive open has A and P) 7) The door opens. (intransitive open has a patient-like S) 8) Carl opens. (intransitive open cannot have an agent-like' S)

Unaligned ambitransitive verbs
German:

9) Dietlind kocht eine Suppe. || (transitive kochen has A and P) ‘Dietlind is cooking a soup.’ || 10) Dietlind kocht. || (intransitive kochen can have an agent-like S) ‘Dietlind is cooking (something).’ || 11) Die Suppe kocht. || (intransitive kochen'' can have a patient-like S) ‘The soup is being cooked (by somebody).’ ||