Harlock \Har"lock\ (h[aum]r"l[o^]k), n. Probably a corruption either of charlock or hardock. --Drayton. [1913 Webster]

Source: The Collaborative International Dictionary of English v.0.48
 

Mustard \Mus"tard\, n. [OF. moustarde, F. moutarde, fr. L. mustum must, -- mustard was prepared for use by being mixed with must. See Must, n.]

1. (Bot.) The name of several cruciferous plants of the genus Brassica (formerly Sinapis), as white mustard (Brassica alba), black mustard (Brassica Nigra), wild mustard or charlock (Brassica Sinapistrum). [1913 Webster]

Note: There are also many herbs of the same family which are called mustard, and have more or less of the flavor of the true mustard; as, bowyer's mustard (Lepidium ruderale); hedge mustard (Sisymbrium officinale); Mithridate mustard (Thlaspi arvense); tower mustard (Arabis perfoliata); treacle mustard (Erysimum cheiranthoides). [1913 Webster]

2. A powder or a paste made from the seeds of black or white mustard, used as a condiment and a rubefacient. Taken internally it is stimulant and diuretic, and in large doses is emetic. [1913 Webster]

Mustard oil (Chem.), a substance obtained from mustard, as a transparent, volatile and intensely pungent oil. The name is also extended to a number of analogous compounds produced either naturally or artificially. [1913 Webster]

Source: The Collaborative International Dictionary of English v.0.48
 

Charlock \Char"lock\, n. [AS. cerlic; the latter part perh. fr. AS. le['a]c leek. Cf. Hemlock.]

(Bot.) A cruciferous plant (Brassica sinapistrum) with yellow flowers; wild mustard. It is troublesome in grain fields. Called also chardock, chardlock, chedlock, and kedlock. [1913 Webster]

Jointed charlock, White charlock, a troublesome weed (Raphanus Raphanistrum) with straw-colored, whitish, or purplish flowers, and jointed pods: wild radish. [1913 Webster]

Source: The Collaborative International Dictionary of English v.0.48
 

charlock

Source: WordNet (r) 2.0
 

Charlock \Char"lock\, n. [AS. cerlic; the latter part perh. fr. AS. le['a]c leek. Cf. Hemlock.]

(Bot.) A cruciferous plant (Brassica sinapistrum) with yellow flowers; wild mustard. It is troublesome in grain fields. Called also chardock, chardlock, chedlock, and kedlock.

Jointed charlock, White charlock, a troublesome weed (Raphanus Raphanistrum) with straw-colored, whitish, or purplish flowers, and jointed pods: wild radish.

Source: Webster's Revised Unabridged Dictionary (1913)