Luke 2:21

The verb συλλαμβάνω, primarily means "to seize, gather, arrest, apprehend, or rally troops."

• To gather or collect together

  • To assemble people or things into a group, to collect forces or fragments of an army (e.g. Hdt. 5.46).

  • To sum up or encapsulate (e.g. Hdt. 3.82; Plat. Men. 76a).

• To grasp or seize

  • To take hold of physically, to grip, or to compress (e.g. Plat. Phaed. 118c; Soph. Aj. 310).

  • To arrest or capture a person (e.g. Soph. Ph. 979, 1003).

• To conceive (biological sense)

  • To become pregnant, either of a woman or an animal (e.g. Arist. H.A. 7.1).

• To help or assist

  • To come to someone’s aid, to help them in a task or with a burden (e.g. Hdt. 6.125; Plat. Leg. 905c).

However, the more standard Greek term for "to conceive" was κύω, with its derivatives κύησις (pregnancy/conception) and κυοφορέω (to be pregnant), but not used in the NT.