engagement

n. commitment, obligation; betrothal, promise to marry; period of employment; battle, fight; (Obstetrics) entrance of the fetal head or lowermost part of the fetus drops and descends into the pelvic canal

An engagement is an agreement or promise to marry, and also refers to the time between proposal and marriage. During this period, a couple is said to be affianced, engaged to be married, or simply engaged.
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Engagement /en·gage·ment/ the entrance of the fetal head or presenting part into the superior pelvic strait. en·gage·ment n. [more]Engagement - Community and Resources

Noun
1. a hostile meeting of opposing military forces in the course of a war; "Grant won a decisive victory in the battle of Chickamauga"; "he lost his romantic ideas about war when he got into a real engagement"
(synonym) battle, conflict, fight
(hypernym) military action, action
(hyponym) Armageddon
(part-holonym) war, warfare
(derivation) engage, wage
(classification) military, armed forces, armed services, military machine, war machine
2. a meeting arranged in advance; "she asked how to avoid kissing at the end of a date"
(synonym) date, appointment
(hypernym) meeting, get together
(hyponym) blind date
(member-meronym) date, escort
3. a mutual promise to marry
(synonym) betrothal, troth
(hypernym) promise
(hyponym) ringing
(derivation) betroth, engage, affiance, plight
4. the act of giving someone a job
(synonym) employment
(hypernym) action
(hyponym) shape-up
(derivation) hire, engage, employ
5. employment for performers or performing groups that lasts for a limited period of time; "the play had bookings throughout the summer"
(synonym) booking
(hypernym) employment, work
(hyponym) gig
6. contact by fitting together; "the engagement of the clutch"; "the meshing of gears"
(synonym) mesh, meshing, interlocking
(hypernym) contact, impinging, striking
(derivation) engage, mesh, lock, operate
7. the act of sharing in the activities of a group; "the teacher tried to increase his students' engagement in class activities"
(synonym) participation, involvement, involution
(antonym) non-engagement, nonparticipation, non-involvement
(hypernym) group action
(hyponym) commitment
(derivation) prosecute, engage, pursue

n. commitment, obligation, promise