Green’s Dictionary of Slang

knock up v.

1. [17C+] to waken; thus knocker up, n., one who wakes people up [knocking on the front or bedroom door].

2. [mid-18C+] to injure, to impair, to wear out, to die, to defeat, thus knock-up n., an impediment, a strain.

3. [17C; early 19C+] (orig. US, also knock) to impregnate.

4. attrib., pertaining to impregnation.

5. [early 19C+] to put together spontaneously, to arrange at short notice.

6. [mid-19C+] to earn a living, usu. with a noun, e.g. knock up a crust.

7. [late 19C+] to amass.

8. (Aus.) to give up, to stop.

In compounds

knock-up money (n.)

[1900s–50s] (US Und.) the profit from a crime.

In phrases

knock up a cheque (v.)

[late 19C–1940s] (Aus.) to earn money for one’s labour.