plod

from The American Heritage® Dictionary of the English Language, 5th Edition.

• intransitive verb To move or walk heavily or laboriously; trudge.
• intransitive verb To work or act perseveringly or monotonously; drudge.
• intransitive verb To trudge along or over.
• noun The act of moving or walking heavily and slowly.
• noun The sound made by a heavy step.

from The Century Dictionary.

• To trudge; travel or work slowly and perseveringly; go on in any pursuit with steady, laborious diligence.
• To lag behind or puzzle upon the scent: said of hounds.
• To go or walk over in a heavy, laboring manner; accomplish by heavy, toilsome walking or exertion.
• noun A puddle.

from the GNU version of the Collaborative International Dictionary of English.

• transitive verb To walk on slowly or heavily.
• intransitive verb To travel slowly but steadily; to trudge.
• intransitive verb To toil; to drudge; especially, to study laboriously and patiently.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun obsolete A puddle.
• noun A slow or labored walk or other motion or activity.
• verb intransitive To walk or move slowly and heavily or laboriously (+ on, through, over).
• verb transitive To trudge over or through.
• noun UK, mildly derogatory, uncountable, usually with "the" the police, police officers
• noun UK, mildly derogatory, countable a police officer, especially a low-ranking one.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the act of walking with a slow heavy gait
• verb walk heavily and firmly, as when weary, or through mud